From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 23 Feb 2012 23:49:27 +0100 From: Willy Tarreau To: Linus Torvalds Cc: Greg Kroah-Hartman , "H. Peter Anvin" , stable@vger.kernel.org, Raphael Prevost , Suresh Siddha , Linux Kernel Mailing List Subject: Re: [PATCH 0/5] i387: stable kernel backport Message-ID: <20120223224927.GC1306@1wt.eu> References: <20120222213253.GA25150@kroah.com> <20120223200905.GA5475@kroah.com> <4F46A1C4.90506@zytor.com> <20120223204832.GA30322@kroah.com> <4F46A6EC.8050804@zytor.com> <20120223211016.GA16275@kroah.com> <20120223215242.GA1306@1wt.eu> <20120223222733.GB1306@1wt.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: On Thu, Feb 23, 2012 at 02:38:42PM -0800, Linus Torvalds wrote: > On Thu, Feb 23, 2012 at 2:27 PM, Willy Tarreau wrote: > > > > OK so indeed I will only be able to check that it boots :-/ > > Well, we could do some trivial test-harness that just forces the issue > with regular timer interrupts (and even without AES-NI). I think Peter > talked about that when we were trying to hunt it down - but I think he > was then able to reproduce the problem without anything special and we > dropped it. > > Essentially, just doing something like > > if (irq_fpu_usable()) { > kernel_fpu_begin(); > kernel_fpu_end(); > } > > in do_irq() and do_softirq() would stress-test things even without > wireless, and even without AES-NI. Interesting... > You'd still need an x86-32 machine to test on, because x86-64 was > immune to this issue. > > But yeah, the impact of this seems to be small enough that for older > kernels (which are likely used on older systems for maintenance > anyway) disabling AES-NI on x86-32 really might be the way to go. I agree. I don't know anybody using AES-NI on purpose on older x86-32 systems! Willy