linux-kernel - Re: [PATCH 1/1] x86/elf: Add a new .note section containing Xfeatures information to x86 core files

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Date: Sat, 16 Mar 2024 11:29:21 +0100
From: Borislav Petkov <bp@...en8.de>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Dave Hansen <dave.hansen@...el.com>,
	Vignesh Balasubramanian <vigbalas@....com>,
	linux-kernel@...r.kernel.org, linux-toolchains@...r.kernel.org,
	mpe@...erman.id.au, npiggin@...il.com, christophe.leroy@...roup.eu,
	aneesh.kumar@...nel.org, naveen.n.rao@...ux.ibm.com,
	ebiederm@...ssion.com, keescook@...omium.org, x86@...nel.org,
	linuxppc-dev@...ts.ozlabs.org, linux-mm@...ck.org,
	jinisusan.george@....com, matz@...e.de, binutils@...rceware.org,
	jhb@...ebsd.org, felix.willgerodt@...el.com
Subject: Re: [PATCH 1/1] x86/elf: Add a new .note section containing
 Xfeatures information to x86 core files

On Sat, Mar 16, 2024 at 12:51:28AM +0100, Thomas Gleixner wrote:
> Anything which is not enumerated in CPUID does not exist in
> XSTATE. Period and end of story.

But why not have a simple buffer definition which doesn't need CPUID?

Also, doing the CPUID thing would need extending the gdb remote protocol
as explained here:

https://lore.kernel.org/r/971d21b7-0309-439e-91b6-234f84da959d@FreeBSD.org

The simple buffer layout won't.

So regardless of where hw is going, I think a simple buffer definition
is always better.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette