Re: [Xen-devel] [PATCH 2/2] xendriverdomain: don't depend on legacy /proc/xen

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Thu, May 12, 2016 at 10:29:30AM -0500, Doug Goldstein wrote:
> xl devd prefers to use /dev/xen/ instead of /proc/xen so the init script
> should use the new interface as well and drop the legacy interface. To
> check for support this uses /sys/hypervisor which has been present since
> 2.6.18 Xen kernels. Fix bad whitespace at the same time.
> 
> Signed-off-by: Doug Goldstein <cardoe@xxxxxxxxxx>
> ---
>  tools/hotplug/Linux/init.d/xendriverdomain.in | 19 ++++---------------
>  1 file changed, 4 insertions(+), 15 deletions(-)
> 
> diff --git a/tools/hotplug/Linux/init.d/xendriverdomain.in 
> b/tools/hotplug/Linux/init.d/xendriverdomain.in
> index 8d4592a..830aa5b 100644
> --- a/tools/hotplug/Linux/init.d/xendriverdomain.in
> +++ b/tools/hotplug/Linux/init.d/xendriverdomain.in
> @@ -27,23 +27,12 @@ test -f $xendriverdomain_config/xendriverdomain && . 
> $xendriverdomain_config/xen
>  XLDEVD_PIDFILE=/var/run/xldevd.pid
>  
>  # not running in Xen dom0 or domU
> -if ! test -d /proc/xen ; then
> +if ! grep -q '^xen' /sys/hypervisor/type ; then
>       exit 0
>  fi
>  
> -# mount xenfs in dom0 or domU with a pv_ops kernel
> -if test "x$1" = xstart && \
> -   ! test -f /proc/xen/capabilities && \
> -   ! grep '^xenfs ' /proc/mounts >/dev/null;
> -then
> -     mount -t xenfs xenfs /proc/xen
> -fi

This unilaterally remove mounting xenfs. We need to keep mounting it
because some applications might use those legacy devices.

I do think we need to avoid breaking old stuff, especially when it is
not to hard to achieve.

> -
>  # run this script only in domU:
> -# no capabilities file in xenlinux domU kernel
> -# empty capabilities file in pv_ops domU kernel
> -if ! test -f /proc/xen/capabilities || \
> -   grep -q "control_d" /proc/xen/capabilities ; then
> +if grep -q '00000000-0000-0000-0000-000000000000' /sys/hypervisor/uuid; then

Here you're relying on the fact that dom0 uuid is all zeros. I don't
think this is documented in Linux, so you can't do it here.

>       exit 0
>  fi
>  
> @@ -52,7 +41,7 @@ do_start () {
>       ${sbindir}/xl devd --pidfile=$XLDEVD_PIDFILE $XLDEVD_ARGS
>  }
>  do_stop () {
> -        echo Stopping xl devd...
> +    echo Stopping xl devd...

Indentation looks wrong. Should use tab here.

>       if read 2>/dev/null <$XLDEVD_PIDFILE pid; then
>               kill $pid
>               while kill -9 $pid >/dev/null 2>&1; do sleep 1; done
> @@ -71,7 +60,7 @@ case "$1" in
>       echo >&2 'Reload not available; use force-reload'; exit 1
>       ;;
>    force-reload|restart)
> -        do_stop
> +    do_stop

Ditto.

>       do_start
>       ;;
>    *)
> -- 
> 2.7.4 (Apple Git-66)
> 

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