[PATCHv2] dracut-module-setup.sh: use auto6 for ipv6

[Pingfan Liu]

The parameter either6 is introduced to dracut by
commit 67354eebbcd4c358b8194ba5fd1ab1cf7dbd42aa
Author: Pingfan Liu 
Date:   Tue Apr 24 16:41:21 2018 +0800

40network: introduce ip=either6 option

But it turns out needless.

On a sensible ipv6 network environment, DHCPv6 can not work properly alone,
because DHCPv6 protocol has no info about the gateway.

An reasonalbe process of ipv6 address set up should look like
   host send: Router Solicitation
   router reply: Router Advertisements

"Router Advertisements" carries many info like gateway, and if it has
other-config flag set, it carries DNS info etc.  As for DHCPv6 address
allocation, it will only start if "Router Advertisements" has the 'managed'
flag set, which directs the host to start a stateful address allocation
from DHCPv6 server.

For more info:
rfc4861: Neighbor Discovery for IP version 6 (IPv6)
rfc5175: IPv6 Router Advertisement Flags Option

Signed-off-by: Pingfan Liu 
---
 dracut-module-setup.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
index 5c41e63..ec1ccc5 100755
--- a/dracut-module-setup.sh
+++ b/dracut-module-setup.sh
@@ -373,7 +373,7 @@ kdump_install_net() {
     if [ -n "$_static" ]; then
         _proto=none
     elif is_ipv6_address $_srcaddr; then
-        _proto=either6
+        _proto=auto6
     else
         _proto=dhcp
     fi

[Kairui Song]

Thank you for the information.

On Mon, Dec 7, 2020 at 12:53 PM Pingfan Liu  wrote:
> The parameter either6 is introduced to dracut by
> commit 67354eebbcd4c358b8194ba5fd1ab1cf7dbd42aa
> Author: Pingfan Liu 
> Date:   Tue Apr 24 16:41:21 2018 +0800
> 40network: introduce ip=either6 option
>
> But it turns out needless.
>
> On a sensible ipv6 network environment, DHCPv6 can not work properly alone,
> because DHCPv6 protocol has no info about the gateway.
>
> An reasonalbe process of ipv6 address set up should look like
>    host send: Router Solicitation
>    router reply: Router Advertisements
>
> "Router Advertisements" carries many info like gateway, and if it has
> other-config flag set, it carries DNS info etc.  As for DHCPv6 address
> allocation, it will only start if "Router Advertisements" has the 'managed'
> flag set, which directs the host to start a stateful address allocation
> from DHCPv6 server.
>
> For more info:
> rfc4861: Neighbor Discovery for IP version 6 (IPv6)
> rfc5175: IPv6 Router Advertisement Flags Option
> Signed-off-by: Pingfan Liu
>
> dracut-module-setup.sh | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
> index 5c41e63..ec1ccc5 100755
> --- a/dracut-module-setup.sh
> +++ b/dracut-module-setup.sh
> @@ -373,7 +373,7 @@ kdump_install_net() {
>      if [ -n "$_static" ]; then
>          _proto=none
>      elif is_ipv6_address $_srcaddr; then
>    _proto=either6
>    _proto=auto6
> else
>        _proto=dhcp
>    fi
>
> --
> 2.7.5

Acked-by: Kairui Song