Re: [PATCH v2 1/3] fadump: use 'zstd' as the default compression method

[Coiby Xu]

On Tue, Nov 22, 2022 at 09:24:24AM +0800, Tao Liu wrote:
> Hi Hari,
>
> On Mon, Nov 21, 2022 at 8:24 PM Hari Bathini  wrote:
> > If available, use 'zstd' compression method to optimize the size of
> > the initrd built with fadump support. Also, 'squash+zstd' is not
> > preferred because more disk space is consumed with 'squash+zstd' due
> > to the additional binaries needed for fadump with squash case.
> > Signed-off-by: Hari Bathini
> >
> > Changes in v2:
> > Updated changelog with why 'zstd' is used for fadump.
>
> Thanks for the update, the patch looks good to me.
>
> Acked-by: Tao Liu

Hi Tao,

When trying to learn how squash affects the memory requirement of kdump,
I notice currently for both F36 and F37, the initramfs is no longer
compressed,

[root@ci-vm-10-0-137-168 t]# file /boot/initramfs-6.1.0-0.rc6.46.fc38.x86_64kdump.img
   /boot/initramfs-6.1.0-0.rc6.46.fc38.x86_64kdump.img: ASCII cpio archive (SVR4 with no CRC)

[root@ci-vm-10-0-139-47 ~]# file /boot/initramfs-6.0.9-200.fc36.x86_64kdump.img
/boot/initramfs-6.0.9-200.fc36.x86_64kdump.img: ASCII cpio archive (SVR4 with no CRC)

This is fc1c79ff ("Seperate dracut and dracut-squash compressor for
zstd") disabls passing "--compress zstd" to dracut when the squashfs
dracut module is going to be used. Is the change intentional? If not,
maybe we should drop this patch and do it in mkdumprd instead.

Btw, it seems "--compress zstd" or "--zstd" no longer compresses the
initramfs in rawhide (2022-11-24) whereas in f36 it works as expected. Another
difference between rawhide and f36 is in 36 with "--zstd" not specified,
dracut will gzip-compress the initramfs while in rawhide, it doesn't
compress the initramfs.
> > mkfadumprd | 6 ++----
> >  1 file changed, 2 insertions(+), 4 deletions(-)
> >
> > diff --git a/mkfadumprd b/mkfadumprd
> > index 36ad645..2fc396c 100644
> > --- a/mkfadumprd
> > +++ b/mkfadumprd
> > @@ -62,11 +62,9 @@ _dracut_isolate_args=(
> >         /usr/lib/dracut/fadump-kernel-modules.txt
> >  )
> >
> > -# Same as setting zstd in mkdumprd
> > +# Use zstd compression method, if available
> >  if ! have_compression_in_dracut_args; then
> >   if is_squash_available && dracut_have_option "--squash-compressor"; then
> >           _dracut_isolate_args+=(--squash-compressor zstd)
> >   elif is_zstd_command_available; then
> >   if is_zstd_command_available; then
> >           _dracut_isolate_args+=(--compress zstd)
> >   fi
> > fi
> >
> > 2.38.1
> > _______________________________________________
> > kexec mailing list -- [e-mail]
> > To unsubscribe send an email to [e-mail]
> > Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/
> > List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines
> > List Archives: https://lists.fedoraproject.org/archives/list/[e-mail]
> > Do not reply to spam, report it: https://pagure.io/fedora-infrastructure/new_issue