> On Mar 31, 2021, at 10:48 AM, Oleksandr Natalenko <oleksandr@xxxxxxxxxxxxxx> wrote: > > Hello. > > On Wed, Mar 31, 2021 at 05:39:25PM +0000, Nick Terrell wrote: >> >> >>> On Mar 30, 2021, at 4:50 AM, Oleksandr Natalenko <oleksandr@xxxxxxxxxxxxxx> wrote: >>> >>> On Tue, Mar 30, 2021 at 01:32:35PM +0200, Piotr Gorski wrote: >>>> kmod 28 supports modules compressed in zstd format so let's add this possibility to kernel. >>>> >>>> Signed-off-by: Piotr Gorski <lucjan.lucjanov@xxxxxxxxx> >>>> --- >>>> Makefile | 7 +++++-- >>>> init/Kconfig | 9 ++++++--- >>>> 2 files changed, 11 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/Makefile b/Makefile >>>> index 5160ff8903c1..82f4f4cc2955 100644 >>>> --- a/Makefile >>>> +++ b/Makefile >>>> @@ -1156,8 +1156,8 @@ endif # INSTALL_MOD_STRIP >>>> export mod_strip_cmd >>>> >>>> # CONFIG_MODULE_COMPRESS, if defined, will cause module to be compressed >>>> -# after they are installed in agreement with CONFIG_MODULE_COMPRESS_GZIP >>>> -# or CONFIG_MODULE_COMPRESS_XZ. >>>> +# after they are installed in agreement with CONFIG_MODULE_COMPRESS_GZIP, >>>> +# CONFIG_MODULE_COMPRESS_XZ, or CONFIG_MODULE_COMPRESS_ZSTD. >>>> >>>> mod_compress_cmd = true >>>> ifdef CONFIG_MODULE_COMPRESS >>>> @@ -1167,6 +1167,9 @@ ifdef CONFIG_MODULE_COMPRESS >>>> ifdef CONFIG_MODULE_COMPRESS_XZ >>>> mod_compress_cmd = $(XZ) --lzma2=dict=2MiB -f >>>> endif # CONFIG_MODULE_COMPRESS_XZ >>>> + ifdef CONFIG_MODULE_COMPRESS_ZSTD >>>> + mod_compress_cmd = $(ZSTD) -T0 --rm -f -q >> >> This will use the default zstd level, level 3. I think it would make more sense to use a high >> compression level. Level 19 would probably be a good choice. That will choose a window >> size of up to 8MB, meaning the decompressor needs to allocate that much memory. If that >> is unacceptable, you could use `zstd -T0 --rm -f -q -19 --zstd=wlog=21`, which will use a >> window size of up to 2MB, to match the XZ command. Note that if the file is smaller than >> the window size, it will be shrunk to the smallest power of two at least as large as the file. > > Please no. We've already done that with initramfs in Arch, and it > increased the time to generate it enormously. > > I understand that building a kernel is a more rare operation than > regenerating initramfs, but still I'd go against hard-coding the level. > And if it should be specified anyway, I'd opt in for an explicit > configuration option. Remember, not all the kernel are built on > build farms... > > FWIW, Piotr originally used level 9 which worked okay, but I insisted > on sending the patch initially without specifying level at all like it is > done for other compressors. If this is a wrong approach, then oh meh, > mea culpa ;). > > Whatever default non-standard compression level you choose, I'm fine > as long as I can change it without editing Makefile. That makes sense to me. I have a deep seated need to compress files as efficiently as possible for widely distributed packages. But, I understand that slow compression significantly impacts build times for quick iteration. I’d be happy with a compression level parameter that defaults to a happy middle. I’m also fine with taking this patch as-is if it is easier, and I can put up another patch that adds a compression level parameter, since I don’t want to block merging this. Best, Nick Terrell > Thanks! > >> >> Best, >> Nick Terrell >> >>>> + endif # CONFIG_MODULE_COMPRESS_ZSTD >>>> endif # CONFIG_MODULE_COMPRESS >>>> export mod_compress_cmd >>>> >>>> diff --git a/init/Kconfig b/init/Kconfig >>>> index 8c2cfd88f6ef..86a452bc2747 100644 >>>> --- a/init/Kconfig >>>> +++ b/init/Kconfig >>>> @@ -2250,8 +2250,8 @@ config MODULE_COMPRESS >>>> bool "Compress modules on installation" >>>> help >>>> >>>> - Compresses kernel modules when 'make modules_install' is run; gzip or >>>> - xz depending on "Compression algorithm" below. >>>> + Compresses kernel modules when 'make modules_install' is run; gzip, >>>> + xz, or zstd depending on "Compression algorithm" below. >>>> >>>> module-init-tools MAY support gzip, and kmod MAY support gzip and xz. >>>> >>>> @@ -2273,7 +2273,7 @@ choice >>>> This determines which sort of compression will be used during >>>> 'make modules_install'. >>>> >>>> - GZIP (default) and XZ are supported. >>>> + GZIP (default), XZ, and ZSTD are supported. >>>> >>>> config MODULE_COMPRESS_GZIP >>>> bool "GZIP" >>>> @@ -2281,6 +2281,9 @@ config MODULE_COMPRESS_GZIP >>>> config MODULE_COMPRESS_XZ >>>> bool "XZ" >>>> >>>> +config MODULE_COMPRESS_ZSTD >>>> + bool "ZSTD" >>>> + >>>> endchoice >>>> >>>> config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS >>>> -- >>>> 2.31.0.97.g1424303384 >>>> >>> >>> Great! >>> >>> Reviewed-by: Oleksandr Natalenko <oleksandr@xxxxxxxxxxxxxx> >>> >>> This works perfectly fine in Arch Linux if accompanied by the >>> following mkinitcpio amendment: [1]. >>> >>> I'm also Cc'ing other people from get_maintainers output just >>> to make this submission more visible. >>> >>> Thanks. >>> >>> [1] https://github.com/archlinux/mkinitcpio/pull/43 >>> >>> -- >>> Oleksandr Natalenko (post-factum) >> > > -- > Oleksandr Natalenko (post-factum)
