linux-kernel - Re: [PATCH] arm64: Allow packing uncompressed images into distro packages

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Message-ID: <ZslQoWbaHqus/KRe@hu-bjorande-lv.qualcomm.com>
Date: Fri, 23 Aug 2024 20:16:49 -0700
From: Bjorn Andersson <quic_bjorande@...cinc.com>
To: Linus Torvalds <torvalds@...ux-foundation.org>
CC: Will Deacon <will@...nel.org>, Bjorn Andersson <andersson@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH] arm64: Allow packing uncompressed images into distro
 packages

On Sat, Aug 24, 2024 at 10:22:54AM +0800, Linus Torvalds wrote:
> On Sat, 24 Aug 2024 at 07:08, Bjorn Andersson <quic_bjorande@...cinc.com> wrote:
> >
> > But the change also made it possible to install "vmlinuz.efi", by
> > setting both options to =y. Was this intentional?
> 
> Absolutely. My arm64 config in fact has EFI_ZBOOT enabled.
> 

Per CONFIG_EFI_ZBOOT help text, the ZBOOT is a compressed image wrapped
in an EFI container. Add to this that both GRUB and Android Boot Loader
happily loads the compressed Image (i.e. Image.gz).

So, in my mind there's: uncompressed Image, compressed Image.gz, and
compressed Image.gz packaged in an EFI application to uncompress itself.

But your change makes more sense than you just wanting the Image.gz,
which puzzled me...

> IOW, the intent of that CONFIG_COMPRESSED_INSTALL was simply to make
> "make install" do the same thing that "make zinstall" used to do.
> 

I was convinced that make zinstall do install the Image.gz, looking at
the Makefiles I am however not able to see how.

> I in fact initially limited the whole COMPRESSED_INSTALL question to
> be *only* for when EFI_ZBOOT is enabled (because that was my
> situation), and privately asked Will if maybe non-EFI people want it.
> So the patch originally had
> 
> +       depends on EFI && EFI_ZBOOT
> 
> and I asked Will
> 
>   Comments? Do the non-EFI_ZBOOT cases also perhaps want this (ie
>   "Image.gz" as opposed to "vmlinuz.efi")?
> 
>   I intentionally tried to make it as limited as possible, but maybe the
>   non-EFI people would want this too?
> 

Just to clarify this point, I only have EFI systems.

> and he thought that it would be better to just make this compressed
> install question be independent of anything else, and literally just
> boil down to "do you want 'make install' to do the same thing as 'make
> zinstall' does?"
> 
> I have *no* idea about what the actual package manager case wants, though.
> 

I looked at, and tried, Arch Linux, Debian, and Fedora. The package
managers effectively unpacks the files, invokes mkinitcpio and feeds the
result to the bootloader. So if you have a bootloader (like
systemd-boot) that doesn't decompress the Image it's asked to load, then
what's being put into the package needs to be uncompressed.

This is why I would like the option to enter the packaging steps with
KBUILD_IMAGE=Image...

I think it would make more sense to have CONFIG_COMPRESSED_INSTALL
represent Image.gz vs Image (compressed vs uncompressed). And if you ask
for an EFI-wrapped Image (ZBOOT) we compress and install that for you
regardless of CONFIG_COMPRESSED_INSTALL.

Regards,
Bjorn