Re: [XEN PATCH] tools/xendomains: Don't auto save/restore/migrate on Arm*

[Peter Hoyes <Peter.Hoyes@xxxxxxx>]

On 19/05/2023 17:24, Anthony PERARD wrote:
> Saving, restoring and migrating domains are not currently supported on
> arm and arm64 platforms, so xendomains prints the warning:
>
>    An error occurred while saving domain:
>    command not implemented
>
> when attempting to run `xendomains stop`. It otherwise continues to shut
> down the domains cleanly, with the unsupported steps skipped.
>
> Also in sysconfig.xendomains, change "Default" to "Example" as the
> real default is an empty value.
>
> Reported-by: Peter Hoyes <Peter.Hoyes@xxxxxxx>
> Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> ---
>
> Peter, what do you think of this approach?
Thanks for preparing this. Just validated that the warning above is not 
present with both qemu-aarch64 and an internal stack.
Tested-by: Peter Hoyes <peter.hoyes@xxxxxxx>

> For reference, there's also a way to findout if a macro exist, with
> AC_CHECK_DECL(), but the libxl.h header depends on other headers that
> needs to be generated.
> ---
>   tools/configure                                    | 11 +++++++++++
>   tools/configure.ac                                 | 13 +++++++++++++
>   tools/hotplug/Linux/init.d/sysconfig.xendomains.in |  4 ++--
>   3 files changed, 26 insertions(+), 2 deletions(-)
>
> diff --git a/tools/configure b/tools/configure
> index 52b4717d01..a722f72c08 100755
> --- a/tools/configure
> +++ b/tools/configure
> @@ -624,6 +624,7 @@ ac_includes_default="\
>   
>   ac_subst_vars='LTLIBOBJS
>   LIBOBJS
> +XENDOMAINS_SAVE_DIR
>   pvshim
>   ninepfs
>   SYSTEMD_LIBS
> @@ -10155,6 +10156,16 @@ if test "$ax_found" = "0"; then :
>   fi
>   
>   
> +case "$host_cpu" in
> +    arm*|aarch64)
> +        XENDOMAINS_SAVE_DIR=
> +        ;;
> +    *)
> +        XENDOMAINS_SAVE_DIR="$XEN_LIB_DIR/save"
> +        ;;
> +esac
> +
> +
>   cat >confcache <<\_ACEOF
>   # This file is a shell script that caches the results of configure
>   # tests run on this system so they can be shared between configure
> diff --git a/tools/configure.ac b/tools/configure.ac
> index 3cccf41960..0f0983f6b7 100644
> --- a/tools/configure.ac
> +++ b/tools/configure.ac
> @@ -517,4 +517,17 @@ AS_IF([test "x$pvshim" = "xy"], [
>   
>   AX_FIND_HEADER([INCLUDE_ENDIAN_H], [endian.h sys/endian.h])
>   
> +dnl Disable autosave of domain in xendomains on shutdown
> +dnl due to missing support. This should be in sync with
> +dnl LIBXL_HAVE_NO_SUSPEND_RESUME in libxl.h
> +case "$host_cpu" in
> +    arm*|aarch64)
> +        XENDOMAINS_SAVE_DIR=
> +        ;;
> +    *)
> +        XENDOMAINS_SAVE_DIR="$XEN_LIB_DIR/save"
> +        ;;
> +esac
> +AC_SUBST(XENDOMAINS_SAVE_DIR)
> +
>   AC_OUTPUT()
> diff --git a/tools/hotplug/Linux/init.d/sysconfig.xendomains.in 
> b/tools/hotplug/Linux/init.d/sysconfig.xendomains.in
> index f61ef9c4d1..3c49f18bb0 100644
> --- a/tools/hotplug/Linux/init.d/sysconfig.xendomains.in
> +++ b/tools/hotplug/Linux/init.d/sysconfig.xendomains.in
> @@ -45,7 +45,7 @@ XENDOMAINS_CREATE_USLEEP=5000000
>   XENDOMAINS_MIGRATE=""
>   
>   ## Type: string
> -## Default: @XEN_LIB_DIR@/save
> +## Example: @XEN_LIB_DIR@/save
>   #
>   # Directory to save running domains to when the system (dom0) is
>   # shut down. Will also be used to restore domains from if # XENDOMAINS_RESTORE
> @@ -53,7 +53,7 @@ XENDOMAINS_MIGRATE=""
>   # (e.g. because you rather shut domains down).
>   # If domain saving does succeed, SHUTDOWN will not be executed.
>   #
> -XENDOMAINS_SAVE=@XEN_LIB_DIR@/save
> +XENDOMAINS_SAVE=@XENDOMAINS_SAVE_DIR@
>   
>   ## Type: string
>   ## Default: "--wait"