Re: [GIT PULL] EFI updates for v6.15

[Ingo Molnar <mingo@kernel.org>]

* Ard Biesheuvel <ardb@kernel.org> wrote:

> > Look into arch/x86/lib/ and you'll see that EFI functionality 
> > doesn't really fit there.
> 
> Again, EFI is only one aspect of this. The SEV-SNP startup code and 
> the early 5-level paging are used by non-EFI boot as well. But they 
> suffer from the same issue (C code that runs so early that it does 
> not tolerate ordinary non-PIC codegen with instrumentation etc)
> 
> Should we maybe classify this as startup code? And put it in 
> arch/x86/boot/startup or arch/x86/kernel/startup?

Yeah, so the canonical place for platform startup code is 
arch/x86/platform/, we could certainly open up arch/x86/platform/efi/ 
there too, in addition to arch/x86/boot/efi/.

Not that it's enforced consistently or historically: in principle we 
ought to have an arch/x86/platform/pc/ directory and move a lot of 
arch/x86/kernel/ there.

Plus the line is a bit fuzzy: as the system is brought up, exactly 
where is the line between boot loading and platform setup: everything 
up to the start_kernel() call is boot code? I don't think that's 
strictly true: for example x86_early_init_platform_quirks() is called 
before start_kernel(), and it's clearly platform setup code.

But in general, platform specific startup and runtime code's best home 
is arch/x86/platform/.

Thanks,

	Ingo