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Date:   Tue, 7 Jul 2020 14:32:12 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Borislav Petkov <bp@alien8.de>,
        Thomas Gleixner <tglx@linutronix.de>, x86@kernel.org
Cc:     Nick Terrell <nickrterrell@gmail.com>,
        linux-kernel@vger.kernel.org, Chris Mason <clm@fb.com>,
        linux-kbuild@vger.kernel.org, gregkh@linuxfoundation.org,
        Petr Malat <oss@malat.biz>, Kernel Team <Kernel-team@fb.com>,
        Adam Borowski <kilobyte@angband.pl>,
        Patrick Williams <patrickw3@fb.com>, rmikey@fb.com,
        mingo@kernel.org, Patrick Williams <patrick@stwcx.xyz>,
        Sedat Dilek <sedat.dilek@gmail.com>,
        Norbert Lange <nolange79@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Nick Terrell <terrelln@fb.com>
Subject: Re: [GIT PULL][PATCH v6 0/8] Add support for ZSTD-compressed kernel
 and initramfs
Message-ID: <202007071422.1060F5932@keescook>
References: <20200707034604.1539157-1-nickrterrell@gmail.com>
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On Mon, Jul 06, 2020 at 08:45:56PM -0700, Nick Terrell wrote:
> From: Nick Terrell <terrelln@fb.com>
> 
> Please pull from
> 
>   git@github.com:terrelln/linux.git tags/v6-zstd
> 
> to get these changes. Alternatively the patchset is included.
> 
> Hi all,
> 
> This patch set adds support for a ZSTD-compressed kernel, ramdisk, and
> initramfs in the kernel boot process. ZSTD-compressed ramdisk and initramfs
> are supported on all architectures. The ZSTD-compressed kernel is only
> hooked up to x86 in this patch set.

Hello x86 maintainers!

I think this series is ready to go. Notes below...

> [...]
>   x86: bump ZO_z_extra_bytes margin for zstd

The above patch is really the only thing that has any external visibility
to kernels that have ZSTD disabled. Given the ratios of memory sizes
involved (an extra 64K when we're dealing with 2MB windows) seems
reasonable to me. If that isn't acceptable, it should be trivial to make
it CONFIG-selectable (like we already do with BOOT_HEAP_SIZE).

What do you think? If the non-x86 parts should land first in -mm, I
guess that would be okay, but I think it makes sense for all of this to
go via -tip.

-Kees

-- 
Kees Cook