linux-kernel - Re: [PATCH V9 21/24] LoongArch: Add zboot (compressed kernel) support

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Message-ID: <Ym4qNILcz+W7dC9i@shell.armlinux.org.uk>
Date:   Sun, 1 May 2022 07:35:32 +0100
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Huacai Chen <chenhuacai@...il.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Huacai Chen <chenhuacai@...ngson.cn>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Airlie <airlied@...ux.ie>,
        Jonathan Corbet <corbet@....net>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Xuefeng Li <lixuefeng@...ngson.cn>,
        Yanteng Si <siyanteng@...ngson.cn>,
        Guo Ren <guoren@...nel.org>, Xuerui Wang <kernel@...0n.name>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Ard Biesheuvel <ardb@...nel.org>,
        linux-efi <linux-efi@...r.kernel.org>
Subject: Re: [PATCH V9 21/24] LoongArch: Add zboot (compressed kernel) support

On Sun, May 01, 2022 at 01:22:25PM +0800, Huacai Chen wrote:
> Hi, Arnd,
> 
> On Sat, Apr 30, 2022 at 7:02 PM Arnd Bergmann <arnd@...db.de> wrote:
> >
> > On Sat, Apr 30, 2022 at 11:05 AM Huacai Chen <chenhuacai@...ngson.cn> wrote:
> > >
> > > This patch adds zboot (self-extracting compressed kernel) support, all
> > > existing in-kernel compressing algorithm and efistub are supported.
> > >
> > > Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
> >
> > I have no objections to adding a decompressor in principle, and
> > the implementation seems reasonable. However, I think we should try to
> > be consistent between architectures. On both arm64 and riscv, the
> > maintainers decided to not include a decompressor and instead leave
> > it up to the boot loader to decompress the kernel and enter it from there.
> X86, ARM32 and MIPS already support self-extracting kernel, and in
> 5.17 we even support self-extracting modules. So I think a
> self-extracting kernel is better than a pure compressed kernel.

FYI, kernel modules are not self-extracting. They don't contain the code
to do the decompression - that is contained within the kernel, and it is
the kernel that does the decompression. The userspace tooling tells the
kernel that the module is compressed.

-- 
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