4gb seg fixup, process on FC6 domU

[Asrai khn]

Hi,

We are running xen on fc6 host and all domU are also fc6, the only issue we
are currently facing is getting lot of error messages in logs

Dec 20 13:06:37  kernel: 4gb seg fixup, process syslogd (pid 873), cs:ip
73:00259ea0
Dec 20 13:06:37  kernel: 4gb seg fixup, process klogd (pid 876), cs:ip
73:001e63a0
Dec 20 13:06:37  kernel: 4gb seg fixup, process klogd (pid 876), cs:ip
73:00268e50
Dec 20 13:06:37  kernel: 4gb seg fixup, process klogd (pid 876), cs:ip
73:001e63a0
Dec 20 13:06:42  kernel: printk: 21 messages suppressed.
Dec 20 13:06:42  kernel: 4gb seg fixup, process master (pid 997), cs:ip
73:003b3cfc
Dec 20 13:06:48  kernel: printk: 30 messages suppressed.
Dec 20 13:06:48  kernel: 4gb seg fixup, process sshd (pid 1121), cs:ip
73:003a4cfc
Dec 20 13:06:50  kernel: printk: 57 messages suppressed.
Dec 20 13:06:50  kernel: 4gb seg fixup, process sshd (pid 1121), cs:ip
73:003a4cfc

getting these error eventually for all processes and on all fc6 domU, I have
tried the fix mention in one of thread ie ..

I've done all of that without success. Any other ideas?

I've renamed /lib/tls to /lib/tls.disabled and echo 'hwcap 0 nosegneg' >
/etc/ld.so.conf.d/libc6-xen.conf

But still getting these error message in domU log file and also on
console when access it via console which makes domU console unusable.

Any help in this regards, will be greatly appreciated.

Thanks. Askar

[Daniel P. Berrange]

On Wed, Dec 20, 2006 at 06:28:03PM +0500, Asrai khn wrote:
>  Hi,
>  
>  We are running xen on fc6 host and all domU are also fc6, the only issue we
>  are currently facing is getting lot of error messages in logs
>  
>  Dec 20 13:06:37  kernel: 4gb seg fixup, process syslogd (pid 873), cs:ip
>  73:00259ea0
>  Dec 20 13:06:37  kernel: 4gb seg fixup, process klogd (pid 876), cs:ip
>  73:001e63a0
>  Dec 20 13:06:37  kernel: 4gb seg fixup, process klogd (pid 876), cs:ip
>  73:00268e50
>  Dec 20 13:06:37  kernel: 4gb seg fixup, process klogd (pid 876), cs:ip
>  73:001e63a0
>  Dec 20 13:06:42  kernel: printk: 21 messages suppressed.
>  Dec 20 13:06:42  kernel: 4gb seg fixup, process master (pid 997), cs:ip
>  73:003b3cfc
>  Dec 20 13:06:48  kernel: printk: 30 messages suppressed.
>  Dec 20 13:06:48  kernel: 4gb seg fixup, process sshd (pid 1121), cs:ip
>  73:003a4cfc
>  Dec 20 13:06:50  kernel: printk: 57 messages suppressed.
>  Dec 20 13:06:50  kernel: 4gb seg fixup, process sshd (pid 1121), cs:ip
>  73:003a4cfc
>  
>  getting these error eventually for all processes and on all fc6 domU, I have
>  tried the fix mention in one of thread ie ..
>  
>  I've done all of that without success. Any other ideas?
>  
>  I've renamed /lib/tls to /lib/tls.disabled and echo 'hwcap 0 nosegneg' >
>  /etc/ld.so.conf.d/libc6-xen.conf 
Both of those are redundant/wrong for FC6.

First, there is no separate /lib/tls anymore - FC6 ditched old pthreads
implementation, and the new NPTL is the default in /lib. So renaming the
empty /lib/tls directory is irrelevant.

Second, the 'hwcap 0 nosegneg' stuff is automatically installed by the
Xen kernel RPM, eg

  $ rpm -qf /etc/ld.so.conf.d/kernelcap-2.6.18-1.2868.fc6.conf
  kernel-xen-2.6.18-1.2868.fc6

  $ cat /etc/ld.so.conf.d/kernelcap-2.6.18-1.2868.fc6.conf 
  # This directive teaches ldconfig to search in nosegneg subdirectories
  # and cache the DSOs there with extra bit 0 set in their hwcap match
  # fields.  In Xen guest kernels, the vDSO tells the dynamic linker to
  # search in nosegneg subdirectories and to match this extra hwcap bit
  # in the ld.so.cache file.
  hwcap 0 nosegneg

>  But still getting these error message in domU log file and also on
>  console when access it via console which makes domU console unusable. 
What kernel version are you running & what kernel-xen & libc RPMs are 
installed in your guest showing this problem. Also are they successfully
(eg, rpm -V kernel-xen  libc)

Dan.
-- 
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[Asrai khn]

Hi Dan,




Both of those are redundant/wrong for FC6.
>  First, there is no separate /lib/tls anymore - FC6 ditched old pthreads
>  implementation, and the new NPTL is the default in /lib. So renaming the
>  empty /lib/tls directory is irrelevant.
>
>  Second, the 'hwcap 0 nosegneg' stuff is automatically installed by the
>  Xen kernel RPM, eg
>
>    $ rpm -qf /etc/ld.so.conf.d/kernelcap-2.6.18-1.2868.fc6.conf
>    kernel-xen-2.6.18-1.2868.fc6 

When i do this on host  machine gives me...

rpm -qf /etc/ld.so.conf.d/kernelcap-2.6.18-1.2849.fc6.conf
kernel-xen-2.6.18-1.2849.fc6

but gives nothing on guest, i don't have /etc/ld.so.conf.d/kernelcap-
2.6.18-1.2849.fc6.conf on guests

  $ cat /etc/ld.so.conf.d/kernelcap-2.6.18-1.2868.fc6.conf
>    # This directive teaches ldconfig to search in nosegneg
> subdirectories
>    # and cache the DSOs there with extra bit 0 set in their hwcap match
>    # fields.  In Xen guest kernels, the vDSO tells the dynamic linker to
>    # search in nosegneg subdirectories and to match this extra hwcap bit
>    # in the ld.so.cache file.
>    hwcap 0 nosegneg
>
>  > But still getting these error message in domU log file and also on
>  > console when access it via console which makes domU console unusable.
>
>  What kernel version are you running & what kernel-xen & libc RPMs are
>  installed in your guest showing this problem. Also are they successfully
>  (eg, rpm -V kernel-xen  libc) 

I'm launching  guest using xm create vms.cfg

and vms.cfg is as under

kernel = "/boot/vmlinuz-2.6.18-1.2849.fc6xen"
ramdisk = "/boot/initrd-2.6.18-1.2849.fc6xen-domU.img"
memory = 128
name = "xxxx"
#vif = [ 'mac=00:16:3e:11:69:85, bridge=xenbr0' ]
vif = [ 'ip=66.xxx.xxx.xxx' ]
disk = ['tap:aio:/var/uml/vm3/root,sda1,w',
'tap:aio:/var/uml/vm3/var,sda2,w', 'tap:aio:/var/uml/vm3/swap,sda3,w']
root = "/dev/sda1 ro"
on_reboot   = 'restart'
on_crash    = 'restart'

So the kernel running on guest ... and i have also copied the xen kernel
modules /lib/modules/ on guest disk image by mounting it.

uname -r
2.6.18-1.2849.fc6xen

Secondly the default initrd for xen kernel that come with fc6 fails to start
our guest so i have created initrd manually by ...

mkinitrd -f --with=xennet --preload=xenblk /boot/initrd-
2.6.18-1.2849.fc6xen-domU.img 2.6.18-1.2849.fc6xen

and then use this initrd for 'ramdisk' in vms.cfg

Thanks.