From: Borislav Petkov <bp@alien8.de>
To: Krzysztof Mazur <krzysiek@podlesie.net>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH] x86/lib: don't use MMX before FPU initialization
Date: Tue, 12 Jan 2021 01:09:23 +0100 [thread overview]
Message-ID: <20210112000923.GK25645@zn.tnic> (raw)
In-Reply-To: <20201228160631.32732-1-krzysiek@podlesie.net>
On Mon, Dec 28, 2020 at 05:06:31PM +0100, Krzysztof Mazur wrote:
> When enabled, the MMX 3DNow! optimized memcpy() is used very early,
> even before FPU is initialized. It worked fine, but commit
> 7ad816762f9bf89e940e618ea40c43138b479e10 ("x86/fpu: Reset MXCSR
> to default in kernel_fpu_begin()") broke that. After that commit
> the kernel crashes just after "Booting the kernel." message.
Have you figured out in the meantime what exactly is causing the
breakage?
Does it boot if you comment out
+ if (boot_cpu_has(X86_FEATURE_FPU))
+ asm volatile ("fninit");
in kernel_fpu_begin()?
I'm guessing K7 doesn't have X86_FEATURE_XMM so the LDMXCSR won't
matter...
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2021-01-12 0:40 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-28 16:06 Krzysztof Mazur
2021-01-12 0:09 ` Borislav Petkov [this message]
2021-01-14 9:22 ` Krzysztof Mazur
2021-01-14 9:44 ` Borislav Petkov
2021-01-14 12:36 ` Krzysztof Mazur
2021-01-14 14:07 ` Borislav Petkov
2021-01-14 14:51 ` Krzysztof Mazur
2021-01-14 16:31 ` Andy Lutomirski
2021-01-15 0:05 ` Krzysztof Mazur
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