[PATCH] kdump.sysconfig: use KDUMP_COMMANDLINE_REMOVE

[Dangyi Liu]

Use KDUMP_COMMANDLINE_REMOVE config instead of hardcode them in
kdumpctl. System admins can also specify what to remove as they like.

However, this patch makes a change that kdump command line from
KDUMP_COMMANDLINE will not be trimmed any more.

Signed-off-by: Dangyi Liu <dliu(a)redhat.com&gt;
Cc: Dave Young <dyoung(a)redhat.com&gt;
Cc: Minfei Huang <mhuang(a)redhat.com&gt;
---
 kdump.sysconfig         | 4 ++++
 kdump.sysconfig.i386    | 4 ++++
 kdump.sysconfig.ppc64   | 4 ++++
 kdump.sysconfig.ppc64le | 4 ++++
 kdump.sysconfig.s390x   | 4 ++++
 kdump.sysconfig.x86_64  | 4 ++++
 kdumpctl                | 3 +--
 7 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/kdump.sysconfig b/kdump.sysconfig
index effe466..f93aa25 100644
--- a/kdump.sysconfig
+++ b/kdump.sysconfig
@@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
 # /proc/cmdline
 KDUMP_COMMANDLINE=""
 
+# This variable lets us remove arguments from the current kdump commandline.
+# This only works when the command line is taken from /proc/cmdline.
+KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
slub_debug"
+
 # This variable lets us append arguments to the current kdump commandline
 # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
 KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 reset_devices"
diff --git a/kdump.sysconfig.i386 b/kdump.sysconfig.i386
index bb7a6e5..b6ca58b 100644
--- a/kdump.sysconfig.i386
+++ b/kdump.sysconfig.i386
@@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
 # /proc/cmdline
 KDUMP_COMMANDLINE=""
 
+# This variable lets us remove arguments from the current kdump commandline.
+# This only works when the command line is taken from /proc/cmdline.
+KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
slub_debug"
+
 # This variable lets us append arguments to the current kdump commandline
 # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
 KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices numa=off
udev.children-max=2 panic=10 rootflags=nofail transparent_hugepage=never"
diff --git a/kdump.sysconfig.ppc64 b/kdump.sysconfig.ppc64
index dd09598..de2364e 100644
--- a/kdump.sysconfig.ppc64
+++ b/kdump.sysconfig.ppc64
@@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
 # /proc/cmdline
 KDUMP_COMMANDLINE=""
 
+# This variable lets us remove arguments from the current kdump commandline.
+# This only works when the command line is taken from /proc/cmdline.
+KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
slub_debug"
+
 # This variable lets us append arguments to the current kdump commandline
 # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
 KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 noirqdistrib reset_devices
cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10
rootflags=nofail kvm_cma_resv_ratio=0 transparent_hugepage=never"
diff --git a/kdump.sysconfig.ppc64le b/kdump.sysconfig.ppc64le
index dd09598..de2364e 100644
--- a/kdump.sysconfig.ppc64le
+++ b/kdump.sysconfig.ppc64le
@@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
 # /proc/cmdline
 KDUMP_COMMANDLINE=""
 
+# This variable lets us remove arguments from the current kdump commandline.
+# This only works when the command line is taken from /proc/cmdline.
+KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
slub_debug"
+
 # This variable lets us append arguments to the current kdump commandline
 # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
 KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 noirqdistrib reset_devices
cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10
rootflags=nofail kvm_cma_resv_ratio=0 transparent_hugepage=never"
diff --git a/kdump.sysconfig.s390x b/kdump.sysconfig.s390x
index b103a88..9fce28d 100644
--- a/kdump.sysconfig.s390x
+++ b/kdump.sysconfig.s390x
@@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
 # /proc/cmdline
 KDUMP_COMMANDLINE=""
 
+# This variable lets us remove arguments from the current kdump commandline.
+# This only works when the command line is taken from /proc/cmdline.
+KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
slub_debug"
+
 # This variable lets us append arguments to the current kdump commandline
 # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
 KDUMP_COMMANDLINE_APPEND="nr_cpus=1 cgroup_disable=memory numa=off
udev.children-max=2 panic=10 rootflags=nofail transparent_hugepage=never"
diff --git a/kdump.sysconfig.x86_64 b/kdump.sysconfig.x86_64
index 7991d68..fc2961d 100644
--- a/kdump.sysconfig.x86_64
+++ b/kdump.sysconfig.x86_64
@@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
 # /proc/cmdline
 KDUMP_COMMANDLINE=""
 
+# This variable lets us remove arguments from the current kdump commandline.
+# This only works when the command line is taken from /proc/cmdline.
+KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
slub_debug"
+
 # This variable lets us append arguments to the current kdump commandline
 # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
 KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices cgroup_disable=memory
mce=off numa=off udev.children-max=2 panic=10 rootflags=nofail acpi_no_memhotplug
transparent_hugepage=never"
diff --git a/kdumpctl b/kdumpctl
index 9f7e56b..3b0760b 100755
--- a/kdumpctl
+++ b/kdumpctl
@@ -102,11 +102,10 @@ prepare_cmdline()
 	local cmdline;
 	if [ -z "$KDUMP_COMMANDLINE" ]; then
 		cmdline=`cat /proc/cmdline`
+		cmdline=`remove_cmdline_param "$cmdline" ${KDUMP_COMMANDLINE_REMOVE}`
 	else
 		cmdline=${KDUMP_COMMANDLINE}
 	fi
-	cmdline=`remove_cmdline_param "$cmdline" crashkernel hugepages hugepagesz
panic_on_warn slub_debug`
-
 
 	cmdline="${cmdline} ${KDUMP_COMMANDLINE_APPEND}"
 
-- 
2.4.3

[Minfei Huang]

On 10/19/15 at 04:29pm, Dangyi Liu wrote:
>  Use KDUMP_COMMANDLINE_REMOVE config instead of hardcode them in
>  kdumpctl. System admins can also specify what to remove as they like.
>  
>  However, this patch makes a change that kdump command line from
>  KDUMP_COMMANDLINE will not be trimmed any more.
>  
>  Signed-off-by: Dangyi Liu <dliu(a)redhat.com&gt;
>  Cc: Dave Young <dyoung(a)redhat.com&gt;
>  Cc: Minfei Huang <mhuang(a)redhat.com&gt;
>  ---
>   kdump.sysconfig         | 4 ++++
>   kdump.sysconfig.i386    | 4 ++++
>   kdump.sysconfig.ppc64   | 4 ++++
>   kdump.sysconfig.ppc64le | 4 ++++
>   kdump.sysconfig.s390x   | 4 ++++
>   kdump.sysconfig.x86_64  | 4 ++++
>   kdumpctl                | 3 +--
>   7 files changed, 25 insertions(+), 2 deletions(-)
>  
>  diff --git a/kdump.sysconfig b/kdump.sysconfig
>  index effe466..f93aa25 100644
>  --- a/kdump.sysconfig
>  +++ b/kdump.sysconfig
>  @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>   # /proc/cmdline
>   KDUMP_COMMANDLINE=""
>   
>  +# This variable lets us remove arguments from the current kdump commandline.
>  +# This only works when the command line is taken from /proc/cmdline.
>  +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  +
>   # This variable lets us append arguments to the current kdump commandline
>   # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>   KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 reset_devices"
>  diff --git a/kdump.sysconfig.i386 b/kdump.sysconfig.i386
>  index bb7a6e5..b6ca58b 100644
>  --- a/kdump.sysconfig.i386
>  +++ b/kdump.sysconfig.i386
>  @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>   # /proc/cmdline
>   KDUMP_COMMANDLINE=""
>   
>  +# This variable lets us remove arguments from the current kdump commandline.
>  +# This only works when the command line is taken from /proc/cmdline.
>  +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  +
>   # This variable lets us append arguments to the current kdump commandline
>   # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>   KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices numa=off
> udev.children-max=2 panic=10 rootflags=nofail transparent_hugepage=never"
>  diff --git a/kdump.sysconfig.ppc64 b/kdump.sysconfig.ppc64
>  index dd09598..de2364e 100644
>  --- a/kdump.sysconfig.ppc64
>  +++ b/kdump.sysconfig.ppc64
>  @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>   # /proc/cmdline
>   KDUMP_COMMANDLINE=""
>   
>  +# This variable lets us remove arguments from the current kdump commandline.
>  +# This only works when the command line is taken from /proc/cmdline.
>  +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  +
>   # This variable lets us append arguments to the current kdump commandline
>   # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>   KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 noirqdistrib reset_devices
> cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10
> rootflags=nofail kvm_cma_resv_ratio=0 transparent_hugepage=never"
>  diff --git a/kdump.sysconfig.ppc64le b/kdump.sysconfig.ppc64le
>  index dd09598..de2364e 100644
>  --- a/kdump.sysconfig.ppc64le
>  +++ b/kdump.sysconfig.ppc64le
>  @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>   # /proc/cmdline
>   KDUMP_COMMANDLINE=""
>   
>  +# This variable lets us remove arguments from the current kdump commandline.
>  +# This only works when the command line is taken from /proc/cmdline.
>  +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  +
>   # This variable lets us append arguments to the current kdump commandline
>   # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>   KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 noirqdistrib reset_devices
> cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10
> rootflags=nofail kvm_cma_resv_ratio=0 transparent_hugepage=never"
>  diff --git a/kdump.sysconfig.s390x b/kdump.sysconfig.s390x
>  index b103a88..9fce28d 100644
>  --- a/kdump.sysconfig.s390x
>  +++ b/kdump.sysconfig.s390x
>  @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>   # /proc/cmdline
>   KDUMP_COMMANDLINE=""
>   
>  +# This variable lets us remove arguments from the current kdump commandline.
>  +# This only works when the command line is taken from /proc/cmdline.
>  +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  +
>   # This variable lets us append arguments to the current kdump commandline
>   # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>   KDUMP_COMMANDLINE_APPEND="nr_cpus=1 cgroup_disable=memory numa=off
> udev.children-max=2 panic=10 rootflags=nofail transparent_hugepage=never"
>  diff --git a/kdump.sysconfig.x86_64 b/kdump.sysconfig.x86_64
>  index 7991d68..fc2961d 100644
>  --- a/kdump.sysconfig.x86_64
>  +++ b/kdump.sysconfig.x86_64
>  @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>   # /proc/cmdline
>   KDUMP_COMMANDLINE=""
>   
>  +# This variable lets us remove arguments from the current kdump commandline.
>  +# This only works when the command line is taken from /proc/cmdline.
>  +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  +
>   # This variable lets us append arguments to the current kdump commandline
>   # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>   KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices cgroup_disable=memory
> mce=off numa=off udev.children-max=2 panic=10 rootflags=nofail acpi_no_memhotplug
> transparent_hugepage=never"
>  diff --git a/kdumpctl b/kdumpctl
>  index 9f7e56b..3b0760b 100755
>  --- a/kdumpctl
>  +++ b/kdumpctl
>  @@ -102,11 +102,10 @@ prepare_cmdline()
>   	local cmdline;
>   	if [ -z "$KDUMP_COMMANDLINE" ]; then
>   		cmdline=`cat /proc/cmdline`
>  +		cmdline=`remove_cmdline_param "$cmdline" ${KDUMP_COMMANDLINE_REMOVE}`
>   	else
>   		cmdline=${KDUMP_COMMANDLINE}
>   	fi
>  -	cmdline=`remove_cmdline_param "$cmdline" crashkernel hugepages hugepagesz
> panic_on_warn slub_debug`
>  -
>   
>   	cmdline="${cmdline} ${KDUMP_COMMANDLINE_APPEND}" 
It's better to remove/add command parameters, if KDUMP_COMMANDLINE is
none, otherwise we shouldn't do anything.
Also IMHO, we may append the command parameters before removing the
parameters in KDUMP_COMMANDLINE_REMOVE.

  	if [ -z "$KDUMP_COMMANDLINE" ]; then
  		cmdline=`cat /proc/cmdline`
 +		cmdline="${cmdline} ${KDUMP_COMMANDLINE_APPEND}"
 +		cmdline=`remove_cmdline_param "$cmdline" ${KDUMP_COMMANDLINE_REMOVE}`
  	else
  		cmdline=${KDUMP_COMMANDLINE}
  	fi
 -	cmdline=`remove_cmdline_param "$cmdline" crashkernel hugepages hugepagesz
panic_on_warn slub_debug`
 -

Thanks
Minfei
  

>   
>  -- 
>  2.4.3
>

[Dangyi Liu]

On Mon, 2015-10-19 at 17:02 +0800, Minfei Huang wrote:
>  It's better to remove/add command parameters, if
> KDUMP_COMMANDLINE is
>  none, otherwise we shouldn't do anything.
>  Also IMHO, we may append the command parameters before removing the
>  parameters in KDUMP_COMMANDLINE_REMOVE.
>  
>          if [ -z "$KDUMP_COMMANDLINE" ]; then
>                  cmdline=`cat /proc/cmdline`
>   +              cmdline="${cmdline} ${KDUMP_COMMANDLINE_APPEND}"
>   +              cmdline=`remove_cmdline_param "$cmdline"
>  ${KDUMP_COMMANDLINE_REMOVE}`
>          else
>                  cmdline=${KDUMP_COMMANDLINE}
>          fi
>   -      cmdline=`remove_cmdline_param "$cmdline" crashkernel
>  hugepages hugepagesz panic_on_warn slub_debug`
>   -
>  
>  Thanks
>  Minfei 
Talked with Dave Yang, this will break the backward compatibility..

Also, for backward compatibility, we need to set a default value for
KDUMP_COMMANDLINE_REMOVE in kdumpctl.

Dangyi

[Baoquan He]

On 10/19/15 at 04:29pm, Dangyi Liu wrote:
>  Use KDUMP_COMMANDLINE_REMOVE config instead of hardcode them in
>  kdumpctl. System admins can also specify what to remove as they like.
>  
>  However, this patch makes a change that kdump command line from
>  KDUMP_COMMANDLINE will not be trimmed any more.
>  
>  Signed-off-by: Dangyi Liu <dliu(a)redhat.com&gt;
>  Cc: Dave Young <dyoung(a)redhat.com&gt;
>  Cc: Minfei Huang <mhuang(a)redhat.com&gt; 
OK, I didn't follow this issue earlier. But I have some questions.
Adding KDUMP_COMMANDLINE_REMOVE to put those kernel-parameters under
/etc/sysconfig means they can be switched by users or admins surely, just
like we do in KDUMP_COMMANDLINE_APPEND. I want to remind that all of
stuffs put in KDUMP_COMMANDLINE_REMOVE are proved helpless for vmcore
dumping. Turning one or several of them could cause bugs, but turning
them off can prevent bugs and don't incur dumping issues. Then I am
wondering why we want them to be turned on by users. E.g for
"crashkernel" could you tell in what cases user want to turn it on in
kdump kernel?

2nd question is if we all agree to put them in KDUMP_COMMANDLINE_REMOVE
do users know what they are used for and why they need remove and in
which case they can be opened?  Do you have a plan to elaborate each of
them?

3rd, I saw you were confused about which one should be handled firstly
about KDUMP_COMMANDLINE_APPEND and KDUMP_COMMANDLINE_REMOVE. This is a
kind of torture we make to put on ourselves. We give users of kdump too
many options.

I personally do not like this idea. But I don't oppose it strongly since
people bring it up.

Thanks
Baoquan

>  ---
>   kdump.sysconfig         | 4 ++++
>   kdump.sysconfig.i386    | 4 ++++
>   kdump.sysconfig.ppc64   | 4 ++++
>   kdump.sysconfig.ppc64le | 4 ++++
>   kdump.sysconfig.s390x   | 4 ++++
>   kdump.sysconfig.x86_64  | 4 ++++
>   kdumpctl                | 3 +--
>   7 files changed, 25 insertions(+), 2 deletions(-)
>  
>  diff --git a/kdump.sysconfig b/kdump.sysconfig
>  index effe466..f93aa25 100644
>  --- a/kdump.sysconfig
>  +++ b/kdump.sysconfig
>  @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>   # /proc/cmdline
>   KDUMP_COMMANDLINE=""
>   
>  +# This variable lets us remove arguments from the current kdump commandline.
>  +# This only works when the command line is taken from /proc/cmdline.
>  +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  +
>   # This variable lets us append arguments to the current kdump commandline
>   # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>   KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 reset_devices"
>  diff --git a/kdump.sysconfig.i386 b/kdump.sysconfig.i386
>  index bb7a6e5..b6ca58b 100644
>  --- a/kdump.sysconfig.i386
>  +++ b/kdump.sysconfig.i386
>  @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>   # /proc/cmdline
>   KDUMP_COMMANDLINE=""
>   
>  +# This variable lets us remove arguments from the current kdump commandline.
>  +# This only works when the command line is taken from /proc/cmdline.
>  +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  +
>   # This variable lets us append arguments to the current kdump commandline
>   # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>   KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices numa=off
> udev.children-max=2 panic=10 rootflags=nofail transparent_hugepage=never"
>  diff --git a/kdump.sysconfig.ppc64 b/kdump.sysconfig.ppc64
>  index dd09598..de2364e 100644
>  --- a/kdump.sysconfig.ppc64
>  +++ b/kdump.sysconfig.ppc64
>  @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>   # /proc/cmdline
>   KDUMP_COMMANDLINE=""
>   
>  +# This variable lets us remove arguments from the current kdump commandline.
>  +# This only works when the command line is taken from /proc/cmdline.
>  +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  +
>   # This variable lets us append arguments to the current kdump commandline
>   # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>   KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 noirqdistrib reset_devices
> cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10
> rootflags=nofail kvm_cma_resv_ratio=0 transparent_hugepage=never"
>  diff --git a/kdump.sysconfig.ppc64le b/kdump.sysconfig.ppc64le
>  index dd09598..de2364e 100644
>  --- a/kdump.sysconfig.ppc64le
>  +++ b/kdump.sysconfig.ppc64le
>  @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>   # /proc/cmdline
>   KDUMP_COMMANDLINE=""
>   
>  +# This variable lets us remove arguments from the current kdump commandline.
>  +# This only works when the command line is taken from /proc/cmdline.
>  +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  +
>   # This variable lets us append arguments to the current kdump commandline
>   # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>   KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 noirqdistrib reset_devices
> cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10
> rootflags=nofail kvm_cma_resv_ratio=0 transparent_hugepage=never"
>  diff --git a/kdump.sysconfig.s390x b/kdump.sysconfig.s390x
>  index b103a88..9fce28d 100644
>  --- a/kdump.sysconfig.s390x
>  +++ b/kdump.sysconfig.s390x
>  @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>   # /proc/cmdline
>   KDUMP_COMMANDLINE=""
>   
>  +# This variable lets us remove arguments from the current kdump commandline.
>  +# This only works when the command line is taken from /proc/cmdline.
>  +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  +
>   # This variable lets us append arguments to the current kdump commandline
>   # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>   KDUMP_COMMANDLINE_APPEND="nr_cpus=1 cgroup_disable=memory numa=off
> udev.children-max=2 panic=10 rootflags=nofail transparent_hugepage=never"
>  diff --git a/kdump.sysconfig.x86_64 b/kdump.sysconfig.x86_64
>  index 7991d68..fc2961d 100644
>  --- a/kdump.sysconfig.x86_64
>  +++ b/kdump.sysconfig.x86_64
>  @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>   # /proc/cmdline
>   KDUMP_COMMANDLINE=""
>   
>  +# This variable lets us remove arguments from the current kdump commandline.
>  +# This only works when the command line is taken from /proc/cmdline.
>  +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  +
>   # This variable lets us append arguments to the current kdump commandline
>   # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>   KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices cgroup_disable=memory
> mce=off numa=off udev.children-max=2 panic=10 rootflags=nofail acpi_no_memhotplug
> transparent_hugepage=never"
>  diff --git a/kdumpctl b/kdumpctl
>  index 9f7e56b..3b0760b 100755
>  --- a/kdumpctl
>  +++ b/kdumpctl
>  @@ -102,11 +102,10 @@ prepare_cmdline()
>   	local cmdline;
>   	if [ -z "$KDUMP_COMMANDLINE" ]; then
>   		cmdline=`cat /proc/cmdline`
>  +		cmdline=`remove_cmdline_param "$cmdline" ${KDUMP_COMMANDLINE_REMOVE}`
>   	else
>   		cmdline=${KDUMP_COMMANDLINE}
>   	fi
>  -	cmdline=`remove_cmdline_param "$cmdline" crashkernel hugepages hugepagesz
> panic_on_warn slub_debug`
>  -
>   
>   	cmdline="${cmdline} ${KDUMP_COMMANDLINE_APPEND}"
>   
>  -- 
>  2.4.3
>  
>  _______________________________________________
>  kexec mailing list
>  kexec(a)lists.fedoraproject.org
>  https://lists.fedoraproject.org/mailman/listinfo/kexec

[Dangyi Liu]

The initial reason why I want to add this configuration is that some boot parameter would
break kdump. For example, kernel developers may use slub_debug, which will cost extra
memory. Normal users may use quiet, which makes kdump debug more difficult. It's
necessary that in some cases admins want to remove some parameters from cmdline. 

And some parameters such as "crash kernel" should never be applied to the second
kernel. We can remove them in kdumpctl directly. 

Thanks,
Dangyi

>  在 2015年10月20日，上午11:46，Baoquan He <bhe(a)redhat.com&gt; 写道：
>  
> > On 10/19/15 at 04:29pm, Dangyi Liu wrote:
> > Use KDUMP_COMMANDLINE_REMOVE config instead of hardcode them in
> > kdumpctl. System admins can also specify what to remove as they like.
> > 
> > However, this patch makes a change that kdump command line from
> > KDUMP_COMMANDLINE will not be trimmed any more.
> > 
> > Signed-off-by: Dangyi Liu <dliu(a)redhat.com&gt;
> > Cc: Dave Young <dyoung(a)redhat.com&gt;
> > Cc: Minfei Huang <mhuang(a)redhat.com&gt;
>  
>  OK, I didn't follow this issue earlier. But I have some questions.
>  Adding KDUMP_COMMANDLINE_REMOVE to put those kernel-parameters under
>  /etc/sysconfig means they can be switched by users or admins surely, just
>  like we do in KDUMP_COMMANDLINE_APPEND. I want to remind that all of
>  stuffs put in KDUMP_COMMANDLINE_REMOVE are proved helpless for vmcore
>  dumping. Turning one or several of them could cause bugs, but turning
>  them off can prevent bugs and don't incur dumping issues. Then I am
>  wondering why we want them to be turned on by users. E.g for
>  "crashkernel" could you tell in what cases user want to turn it on in
>  kdump kernel?
>  
>  2nd question is if we all agree to put them in KDUMP_COMMANDLINE_REMOVE
>  do users know what they are used for and why they need remove and in
>  which case they can be opened?  Do you have a plan to elaborate each of
>  them?
>  
>  3rd, I saw you were confused about which one should be handled firstly
>  about KDUMP_COMMANDLINE_APPEND and KDUMP_COMMANDLINE_REMOVE. This is a
>  kind of torture we make to put on ourselves. We give users of kdump too
>  many options.
>  
>  I personally do not like this idea. But I don't oppose it strongly since
>  people bring it up.
>  
>  Thanks
>  Baoquan
>  
> > ---
> > kdump.sysconfig         | 4 ++++
> > kdump.sysconfig.i386    | 4 ++++
> > kdump.sysconfig.ppc64   | 4 ++++
> > kdump.sysconfig.ppc64le | 4 ++++
> > kdump.sysconfig.s390x   | 4 ++++
> > kdump.sysconfig.x86_64  | 4 ++++
> > kdumpctl                | 3 +--
> > 7 files changed, 25 insertions(+), 2 deletions(-)
> > 
> > diff --git a/kdump.sysconfig b/kdump.sysconfig
> > index effe466..f93aa25 100644
> > --- a/kdump.sysconfig
> > +++ b/kdump.sysconfig
> > @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
> > # /proc/cmdline
> > KDUMP_COMMANDLINE=""
> > 
> > +# This variable lets us remove arguments from the current kdump commandline.
> > +# This only works when the command line is taken from /proc/cmdline.
> > +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
> > +
> > # This variable lets us append arguments to the current kdump commandline
> > # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
> > KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 reset_devices"
> > diff --git a/kdump.sysconfig.i386 b/kdump.sysconfig.i386
> > index bb7a6e5..b6ca58b 100644
> > --- a/kdump.sysconfig.i386
> > +++ b/kdump.sysconfig.i386
> > @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
> > # /proc/cmdline
> > KDUMP_COMMANDLINE=""
> > 
> > +# This variable lets us remove arguments from the current kdump commandline.
> > +# This only works when the command line is taken from /proc/cmdline.
> > +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
> > +
> > # This variable lets us append arguments to the current kdump commandline
> > # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
> > KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices numa=off
> udev.children-max=2 panic=10 rootflags=nofail transparent_hugepage=never"
> > diff --git a/kdump.sysconfig.ppc64 b/kdump.sysconfig.ppc64
> > index dd09598..de2364e 100644
> > --- a/kdump.sysconfig.ppc64
> > +++ b/kdump.sysconfig.ppc64
> > @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
> > # /proc/cmdline
> > KDUMP_COMMANDLINE=""
> > 
> > +# This variable lets us remove arguments from the current kdump commandline.
> > +# This only works when the command line is taken from /proc/cmdline.
> > +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
> > +
> > # This variable lets us append arguments to the current kdump commandline
> > # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
> > KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 noirqdistrib reset_devices
> cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10
> rootflags=nofail kvm_cma_resv_ratio=0 transparent_hugepage=never"
> > diff --git a/kdump.sysconfig.ppc64le b/kdump.sysconfig.ppc64le
> > index dd09598..de2364e 100644
> > --- a/kdump.sysconfig.ppc64le
> > +++ b/kdump.sysconfig.ppc64le
> > @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
> > # /proc/cmdline
> > KDUMP_COMMANDLINE=""
> > 
> > +# This variable lets us remove arguments from the current kdump commandline.
> > +# This only works when the command line is taken from /proc/cmdline.
> > +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
> > +
> > # This variable lets us append arguments to the current kdump commandline
> > # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
> > KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 noirqdistrib reset_devices
> cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10
> rootflags=nofail kvm_cma_resv_ratio=0 transparent_hugepage=never"
> > diff --git a/kdump.sysconfig.s390x b/kdump.sysconfig.s390x
> > index b103a88..9fce28d 100644
> > --- a/kdump.sysconfig.s390x
> > +++ b/kdump.sysconfig.s390x
> > @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
> > # /proc/cmdline
> > KDUMP_COMMANDLINE=""
> > 
> > +# This variable lets us remove arguments from the current kdump commandline.
> > +# This only works when the command line is taken from /proc/cmdline.
> > +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
> > +
> > # This variable lets us append arguments to the current kdump commandline
> > # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
> > KDUMP_COMMANDLINE_APPEND="nr_cpus=1 cgroup_disable=memory numa=off
> udev.children-max=2 panic=10 rootflags=nofail transparent_hugepage=never"
> > diff --git a/kdump.sysconfig.x86_64 b/kdump.sysconfig.x86_64
> > index 7991d68..fc2961d 100644
> > --- a/kdump.sysconfig.x86_64
> > +++ b/kdump.sysconfig.x86_64
> > @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
> > # /proc/cmdline
> > KDUMP_COMMANDLINE=""
> > 
> > +# This variable lets us remove arguments from the current kdump commandline.
> > +# This only works when the command line is taken from /proc/cmdline.
> > +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
> > +
> > # This variable lets us append arguments to the current kdump commandline
> > # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
> > KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices cgroup_disable=memory
> mce=off numa=off udev.children-max=2 panic=10 rootflags=nofail acpi_no_memhotplug
> transparent_hugepage=never"
> > diff --git a/kdumpctl b/kdumpctl
> > index 9f7e56b..3b0760b 100755
> > --- a/kdumpctl
> > +++ b/kdumpctl
> > @@ -102,11 +102,10 @@ prepare_cmdline()
> >    local cmdline;
> >    if [ -z "$KDUMP_COMMANDLINE" ]; then
> >        cmdline=`cat /proc/cmdline`
> > +        cmdline=`remove_cmdline_param "$cmdline"
> ${KDUMP_COMMANDLINE_REMOVE}`
> >    else
> >        cmdline=${KDUMP_COMMANDLINE}
> >    fi
> > -    cmdline=`remove_cmdline_param "$cmdline" crashkernel hugepages
> hugepagesz panic_on_warn slub_debug`
> > -
> > 
> >    cmdline="${cmdline} ${KDUMP_COMMANDLINE_APPEND}"
> > 
> > -- 
> > 2.4.3
> > 
> > _______________________________________________
> > kexec mailing list
> > kexec(a)lists.fedoraproject.org
> > https://lists.fedoraproject.org/mailman/listinfo/kexec
>

[Baoquan He]

On 10/20/15 at 12:32am, Dangyi Liu wrote:
>  The initial reason why I want to add this configuration is that some
> boot parameter would break kdump. For example, kernel developers may use slub_debug, which
> will cost extra memory. Normal users may use quiet, which makes kdump debug more
> difficult. It's necessary that in some cases admins want to remove some parameters
> from cmdline. 
>  
>  And some parameters such as "crash kernel" should never be applied to the
> second kernel. We can remove them in kdumpctl directly.  
OK, if it becomes a one by one check. Let's evaluate each of them, how
about panic_on_warn? This one will nested panic in kdump kernel because
of a warn. This can't be opened.

Next are hugepagexx. This could be opened again by user for curiosity or
efficiency and similar to slub_debug if enough crashkernel memory is
reserved. quiet, should be the same way.

This is about my 1st question. How about the 2nd? About the 3rd
question, that is a annoy and need be considered.

>  > 在 2015年10月20日，上午11:46，Baoquan He <bhe(a)redhat.com&gt; 写道：
>  > 
>  >> On 10/19/15 at 04:29pm, Dangyi Liu wrote:
>  >> Use KDUMP_COMMANDLINE_REMOVE config instead of hardcode them in
>  >> kdumpctl. System admins can also specify what to remove as they like.
>  >> 
>  >> However, this patch makes a change that kdump command line from
>  >> KDUMP_COMMANDLINE will not be trimmed any more.
>  >> 
>  >> Signed-off-by: Dangyi Liu <dliu(a)redhat.com&gt;
>  >> Cc: Dave Young <dyoung(a)redhat.com&gt;
>  >> Cc: Minfei Huang <mhuang(a)redhat.com&gt;
>  > 
>  > OK, I didn't follow this issue earlier. But I have some questions.
>  > Adding KDUMP_COMMANDLINE_REMOVE to put those kernel-parameters under
>  > /etc/sysconfig means they can be switched by users or admins surely, just
>  > like we do in KDUMP_COMMANDLINE_APPEND. I want to remind that all of
>  > stuffs put in KDUMP_COMMANDLINE_REMOVE are proved helpless for vmcore
>  > dumping. Turning one or several of them could cause bugs, but turning
>  > them off can prevent bugs and don't incur dumping issues. Then I am
>  > wondering why we want them to be turned on by users. E.g for
>  > "crashkernel" could you tell in what cases user want to turn it on in
>  > kdump kernel?
>  > 
>  > 2nd question is if we all agree to put them in KDUMP_COMMANDLINE_REMOVE
>  > do users know what they are used for and why they need remove and in
>  > which case they can be opened?  Do you have a plan to elaborate each of
>  > them?
>  > 
>  > 3rd, I saw you were confused about which one should be handled firstly
>  > about KDUMP_COMMANDLINE_APPEND and KDUMP_COMMANDLINE_REMOVE. This is a
>  > kind of torture we make to put on ourselves. We give users of kdump too
>  > many options.
>  > 
>  > I personally do not like this idea. But I don't oppose it strongly since
>  > people bring it up.
>  > 
>  > Thanks
>  > Baoquan
>  > 
>  >> ---
>  >> kdump.sysconfig         | 4 ++++
>  >> kdump.sysconfig.i386    | 4 ++++
>  >> kdump.sysconfig.ppc64   | 4 ++++
>  >> kdump.sysconfig.ppc64le | 4 ++++
>  >> kdump.sysconfig.s390x   | 4 ++++
>  >> kdump.sysconfig.x86_64  | 4 ++++
>  >> kdumpctl                | 3 +--
>  >> 7 files changed, 25 insertions(+), 2 deletions(-)
>  >> 
>  >> diff --git a/kdump.sysconfig b/kdump.sysconfig
>  >> index effe466..f93aa25 100644
>  >> --- a/kdump.sysconfig
>  >> +++ b/kdump.sysconfig
>  >> @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>  >> # /proc/cmdline
>  >> KDUMP_COMMANDLINE=""
>  >> 
>  >> +# This variable lets us remove arguments from the current kdump commandline.
>  >> +# This only works when the command line is taken from /proc/cmdline.
>  >> +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  >> +
>  >> # This variable lets us append arguments to the current kdump commandline
>  >> # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>  >> KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 reset_devices"
>  >> diff --git a/kdump.sysconfig.i386 b/kdump.sysconfig.i386
>  >> index bb7a6e5..b6ca58b 100644
>  >> --- a/kdump.sysconfig.i386
>  >> +++ b/kdump.sysconfig.i386
>  >> @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>  >> # /proc/cmdline
>  >> KDUMP_COMMANDLINE=""
>  >> 
>  >> +# This variable lets us remove arguments from the current kdump commandline.
>  >> +# This only works when the command line is taken from /proc/cmdline.
>  >> +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  >> +
>  >> # This variable lets us append arguments to the current kdump commandline
>  >> # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>  >> KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices numa=off
> udev.children-max=2 panic=10 rootflags=nofail transparent_hugepage=never"
>  >> diff --git a/kdump.sysconfig.ppc64 b/kdump.sysconfig.ppc64
>  >> index dd09598..de2364e 100644
>  >> --- a/kdump.sysconfig.ppc64
>  >> +++ b/kdump.sysconfig.ppc64
>  >> @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>  >> # /proc/cmdline
>  >> KDUMP_COMMANDLINE=""
>  >> 
>  >> +# This variable lets us remove arguments from the current kdump commandline.
>  >> +# This only works when the command line is taken from /proc/cmdline.
>  >> +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  >> +
>  >> # This variable lets us append arguments to the current kdump commandline
>  >> # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>  >> KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 noirqdistrib reset_devices
> cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10
> rootflags=nofail kvm_cma_resv_ratio=0 transparent_hugepage=never"
>  >> diff --git a/kdump.sysconfig.ppc64le b/kdump.sysconfig.ppc64le
>  >> index dd09598..de2364e 100644
>  >> --- a/kdump.sysconfig.ppc64le
>  >> +++ b/kdump.sysconfig.ppc64le
>  >> @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>  >> # /proc/cmdline
>  >> KDUMP_COMMANDLINE=""
>  >> 
>  >> +# This variable lets us remove arguments from the current kdump commandline.
>  >> +# This only works when the command line is taken from /proc/cmdline.
>  >> +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  >> +
>  >> # This variable lets us append arguments to the current kdump commandline
>  >> # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>  >> KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 noirqdistrib reset_devices
> cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10
> rootflags=nofail kvm_cma_resv_ratio=0 transparent_hugepage=never"
>  >> diff --git a/kdump.sysconfig.s390x b/kdump.sysconfig.s390x
>  >> index b103a88..9fce28d 100644
>  >> --- a/kdump.sysconfig.s390x
>  >> +++ b/kdump.sysconfig.s390x
>  >> @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>  >> # /proc/cmdline
>  >> KDUMP_COMMANDLINE=""
>  >> 
>  >> +# This variable lets us remove arguments from the current kdump commandline.
>  >> +# This only works when the command line is taken from /proc/cmdline.
>  >> +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  >> +
>  >> # This variable lets us append arguments to the current kdump commandline
>  >> # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>  >> KDUMP_COMMANDLINE_APPEND="nr_cpus=1 cgroup_disable=memory numa=off
> udev.children-max=2 panic=10 rootflags=nofail transparent_hugepage=never"
>  >> diff --git a/kdump.sysconfig.x86_64 b/kdump.sysconfig.x86_64
>  >> index 7991d68..fc2961d 100644
>  >> --- a/kdump.sysconfig.x86_64
>  >> +++ b/kdump.sysconfig.x86_64
>  >> @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>  >> # /proc/cmdline
>  >> KDUMP_COMMANDLINE=""
>  >> 
>  >> +# This variable lets us remove arguments from the current kdump commandline.
>  >> +# This only works when the command line is taken from /proc/cmdline.
>  >> +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
> slub_debug"
>  >> +
>  >> # This variable lets us append arguments to the current kdump commandline
>  >> # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>  >> KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices
> cgroup_disable=memory mce=off numa=off udev.children-max=2 panic=10 rootflags=nofail
> acpi_no_memhotplug transparent_hugepage=never"
>  >> diff --git a/kdumpctl b/kdumpctl
>  >> index 9f7e56b..3b0760b 100755
>  >> --- a/kdumpctl
>  >> +++ b/kdumpctl
>  >> @@ -102,11 +102,10 @@ prepare_cmdline()
>  >>    local cmdline;
>  >>    if [ -z "$KDUMP_COMMANDLINE" ]; then
>  >>        cmdline=`cat /proc/cmdline`
>  >> +        cmdline=`remove_cmdline_param "$cmdline"
> ${KDUMP_COMMANDLINE_REMOVE}`
>  >>    else
>  >>        cmdline=${KDUMP_COMMANDLINE}
>  >>    fi
>  >> -    cmdline=`remove_cmdline_param "$cmdline" crashkernel hugepages
> hugepagesz panic_on_warn slub_debug`
>  >> -
>  >> 
>  >>    cmdline="${cmdline} ${KDUMP_COMMANDLINE_APPEND}"
>  >> 
>  >> -- 
>  >> 2.4.3
>  >> 
>  >> _______________________________________________
>  >> kexec mailing list
>  >> kexec(a)lists.fedoraproject.org
>  >> https://lists.fedoraproject.org/mailman/listinfo/kexec
>  _______________________________________________
>  kexec mailing list
>  kexec(a)lists.fedoraproject.org
>  https://lists.fedoraproject.org/mailman/listinfo/kexec

[Dangyi Liu]

On Tue, 2015-10-20 at 15:02 +0800, Baoquan He wrote:
>  On 10/20/15 at 12:32am, Dangyi Liu wrote:
>  > The initial reason why I want to add this configuration is that
>  > some boot parameter would break kdump. For example, kernel
>  > developers may use slub_debug, which will cost extra memory. Normal
>  > users may use quiet, which makes kdump debug more difficult. It's
>  > necessary that in some cases admins want to remove some parameters
>  > from cmdline. 
>  > 
>  > And some parameters such as "crash kernel" should never be applied
>  > to the second kernel. We can remove them in kdumpctl directly. 
>  
>  OK, if it becomes a one by one check. Let's evaluate each of them,
>  how
>  about panic_on_warn? This one will nested panic in kdump kernel
>  because
>  of a warn. This can't be opened. 
I didn't mean to put all existing items into the config file. But in
some cases admins do need to remove some boot parameters for the second
kernel. That's why I think maybe we can make it configurable.

I agree with that crashkernel and panic_on_warn should not be
configurable.

>  Next are hugepagexx. This could be opened again by user for
> curiosity
>  or
>  efficiency and similar to slub_debug if enough crashkernel memory is
>  reserved. quiet, should be the same way.
>  
>  This is about my 1st question. How about the 2nd? About the 3rd
>  question, that is a annoy and need be considered.
>  
>  > > 在 2015年10月20日，上午11:46，Baoquan He <bhe(a)redhat.com&gt; 写道：
>  > > 
>  > > > On 10/19/15 at 04:29pm, Dangyi Liu wrote:
>  > > > Use KDUMP_COMMANDLINE_REMOVE config instead of hardcode them in
>  > > > kdumpctl. System admins can also specify what to remove as they
>  > > > like.
>  > > > 
>  > > > However, this patch makes a change that kdump command line from
>  > > > KDUMP_COMMANDLINE will not be trimmed any more.
>  > > > 
>  > > > Signed-off-by: Dangyi Liu <dliu(a)redhat.com&gt;
>  > > > Cc: Dave Young <dyoung(a)redhat.com&gt;
>  > > > Cc: Minfei Huang <mhuang(a)redhat.com&gt;
>  > > 
>  > > OK, I didn't follow this issue earlier. But I have some
>  > > questions.
>  > > Adding KDUMP_COMMANDLINE_REMOVE to put those kernel-parameters
>  > > under
>  > > /etc/sysconfig means they can be switched by users or admins
>  > > surely, just
>  > > like we do in KDUMP_COMMANDLINE_APPEND. I want to remind that all
>  > > of
>  > > stuffs put in KDUMP_COMMANDLINE_REMOVE are proved helpless for
>  > > vmcore
>  > > dumping. Turning one or several of them could cause bugs, but
>  > > turning
>  > > them off can prevent bugs and don't incur dumping issues. Then I
>  > > am
>  > > wondering why we want them to be turned on by users. E.g for
>  > > "crashkernel" could you tell in what cases user want to turn it
>  > > on in
>  > > kdump kernel?
>  > > 
>  > > 2nd question is if we all agree to put them in
>  > > KDUMP_COMMANDLINE_REMOVE
>  > > do users know what they are used for and why they need remove and
>  > > in
>  > > which case they can be opened?  Do you have a plan to elaborate
>  > > each of
>  > > them? 
Only advanced users or instructed users may need to get access to this
config file. For example, we may tell some customers to "add quiet to
KDUMP_COMMANDLINE_REMOVE and send the full log to us", but we cannot
tell them "edit /bin/kdumpctl at line 108 to add quiet".

>  > > 
>  > > 3rd, I saw you were confused about which one should be handled
>  > > firstly
>  > > about KDUMP_COMMANDLINE_APPEND and KDUMP_COMMANDLINE_REMOVE. This
>  > > is a
>  > > kind of torture we make to put on ourselves. We give users of
>  > > kdump too
>  > > many options. 
I think it's better to remove first then append. For example we can
remove all "dydbg" first then add other dynamic debug options.

Dangyi

[Baoquan He]

On 10/20/15 at 03:19pm, Dangyi Liu wrote:
>  Only advanced users or instructed users may need to get access to
> this
>  config file. For example, we may tell some customers to "add quiet to
>  KDUMP_COMMANDLINE_REMOVE and send the full log to us", but we cannot
>  tell them "edit /bin/kdumpctl at line 108 to add quiet". 
Anyone who knows unix/linux knows what they can do to a file under
/etc/. Sometime we can tell people or send a script patch to ask them to
change kdumpctl. Just etc file is formal.

>  
>  > > > 
>  > > > 3rd, I saw you were confused about which one should be handled
>  > > > firstly
>  > > > about KDUMP_COMMANDLINE_APPEND and KDUMP_COMMANDLINE_REMOVE. This
>  > > > is a
>  > > > kind of torture we make to put on ourselves. We give users of
>  > > > kdump too
>  > > > many options.
>  
>  I think it's better to remove first then append. For example we can
>  remove all "dydbg" first then add other dynamic debug options. 
I don't have a good idea about this. Let's your final code. In the end a
clear paragraph need be wrote into howto or other documents.

>  
>  Dangyi
>