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

[Huacai Chen]

Hi, Russell,

On Sun, May 1, 2022 at 2:35 PM Russell King (Oracle)
<linux@xxxxxxxxxxxxxxx> wrote:
>
> 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@xxxxxxxx> wrote:
> > >
> > > On Sat, Apr 30, 2022 at 11:05 AM Huacai Chen <chenhuacai@xxxxxxxxxxx> 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@xxxxxxxxxxx>
> > >
> > > 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.
I call "self-extracting" here means we don't need out-of-kernel help:
kernel decompress doesn't need the bootloader, module decompress
doesn't need kmod.

Huacai
>
> --
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!