From: Peter Zijlstra <peterz@infradead.org>
To: Andy Lutomirski <luto@kernel.org>
Cc: x86@kernel.org, LKML <linux-kernel@vger.kernel.org>,
"Krzysztof Mazur" <krzysiek@podlesie.net>,
"Krzysztof Olędzki" <ole@ans.pl>, "Arnd Bergmann" <arnd@arndb.de>
Subject: Re: [PATCH 1/4] x86/fpu: Add kernel_fpu_begin_mask() to selectively initialize state
Date: Mon, 18 Jan 2021 13:21:32 +0100 [thread overview]
Message-ID: <YAV9TBMZ+Xs9ielC@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <a9630f17c5bcafbfe297a0828c7b6c78b0f6dcbe.1610950681.git.luto@kernel.org>
On Sun, Jan 17, 2021 at 10:20:38PM -0800, Andy Lutomirski wrote:
> - Code that wants MMX doesn't want need MXCSR or FCW initialized.
> _mmx_memcpy(), for example, can run before CR4.OSFXSR gets set, and
> initializing MXCSR will fail.
> +#define KFPU_MMX 0 /* nothing gets initialized */
This... why is that correct?
next prev parent reply other threads:[~2021-01-18 12:23 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-18 6:20 [PATCH 0/4] x86/fpu: Reduce unnecessary FNINIT and MXCSR usage Andy Lutomirski
2021-01-18 6:20 ` [PATCH 1/4] x86/fpu: Add kernel_fpu_begin_mask() to selectively initialize state Andy Lutomirski
2021-01-18 12:21 ` Peter Zijlstra [this message]
2021-01-18 14:03 ` David Laight
2021-01-19 11:08 ` Borislav Petkov
2021-01-18 6:20 ` [PATCH 2/4] x86/mmx: Use KFPU_MMX for MMX string operations Andy Lutomirski
2021-01-18 6:20 ` [PATCH 3/4] x86/fpu: Make the EFI FPU calling convention explicit Andy Lutomirski
2021-01-18 12:13 ` Borislav Petkov
2021-01-18 6:20 ` [PATCH 4/4] x86/fpu/64: Don't FNINIT in kernel_fpu_begin() Andy Lutomirski
2021-01-18 8:25 ` [PATCH 0/4] x86/fpu: Reduce unnecessary FNINIT and MXCSR usage Krzysztof Olędzki
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