linux-kernel - Re: [PATCH] initramfs: restore default compression behaviour

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Date:   Tue, 17 Mar 2020 09:57:33 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        arcml <linux-snps-arc@...ts.infradead.org>,
        Vineet Gupta <Vineet.Gupta1@...opsys.com>,
        Alexey Brodkin <Alexey.Brodkin@...opsys.com>
Subject: Re: [PATCH] initramfs: restore default compression behaviour

On Mon, Mar 16, 2020 at 8:22 PM Eugeniy Paltsev
<Eugeniy.Paltsev@...opsys.com> wrote:
>
> Hi Masahiro,
>
> >From: Masahiro Yamada <masahiroy@...nel.org>
> >Sent: Wednesday, March 11, 2020 23:12
> >To: Eugeniy Paltsev
> >Cc: Linux Kernel Mailing List; arcml; Vineet Gupta; Alexey Brodkin
> >Subject: Re: [PATCH] initramfs: restore default compression behaviour
> >
> >Hi Eugeniy.
> >
> >On Wed, Mar 11, 2020 at 7:22 PM Eugeniy Paltsev
> ><Eugeniy.Paltsev@...opsys.com> wrote:
> >>
> >> Even though INITRAMFS_SOURCE kconfig option isn't set in most of
> >> defconfigs it is used (set) extensively by various build systems.
> >> Commit f26661e12765 ("initramfs: make initramfs compression choice
> >> non-optional") has changed default compression mode. Previously we
> >> compress initramfs using available compression algorithm. Now
> >> we don't use any compression at all by default.
> >> It significantly increases the image size in case of build system
> >> chooses embedded initramfs. Initially I faced with this issue while
> >> using buildroot.
> >>
> >> As of today it's not possible to set preferred compression mode
> >> in target defconfig as this option depends on INITRAMFS_SOURCE
> >> being set.
> >> Modification of build systems doesn't look like good option in this
> >> case as it requires to check against kernel version when setting
> >> compression mode. The reason for this is that kconfig options
> >> describing compression mode was renamed (in same patch series)
> >
> >Which commit?
> >
> >I do not remember the renaming of kconfig options
> >with this regard.
>
> Ok, I've checked it again - looks like I was confused a bit by
> "CONFIG_INITRAMFS_COMPRESSION" option
> as in v5.5 kernel I have in ".config":
> CONFIG_INITRAMFS_COMPRESSION=".gz"
>
> And for v5.6-rc1 I have in ".config":
> CONFIG_INITRAMFS_COMPRESSION_GZIP=y
>
> But they are different options actually...


Right.

There is no prompt for CONFIG_INITRAMFS_COMPRESSION.
So, users have no control of it.

Because this is just a matter of the file extension,
commit 65e00e04e5aea34 moved the logic to Makefile.




-- 
Best Regards
Masahiro Yamada