Re: [PATCH] arm64/cpufeature: annotate arm64_use_ng_mappings with ro_after_init to prevent wrong idmap generation

[Yeoreum Yun]

> On Fri, May 02, 2025 at 06:41:33PM +0200, Ard Biesheuvel wrote:
> > Making arm64_use_ng_mappings __ro_after_init seems like a useful
> > change by itself, so I am not objecting to that. But we don't solve it
> > more fundamentally, please at least add a big fat comment why it is
> > important that the variable remains there.
>
> Maybe something like the section reference checker we use for __init -
> verify that the early C code does not refer anything in the BSS section.

Maybe but it would be better to be checked at compile time (I don't
know it's possible) otherwise, early C code writer should check
mandatroy by calling is_kernel_bss_data() (not exist) for data it refers.

> --
> Catalin

--
Sincerely,
Yeoreum Yun