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Date: Tue, 30 Jun 2015 07:18:00 +0200 From: Ingo Molnar <mingo@...nel.org> To: "H. Peter Anvin" <hpa@...or.com> Cc: Mike Galbraith <umgwanakikbuti@...il.com>, Ingo Molnar <mingo@...e.hu>, LKML <linux-kernel@...r.kernel.org>, Borislav Petkov <bp@...en8.de>, Thomas Gleixner <tglx@...utronix.de>, Andy Lutomirski <luto@...nel.org>, Denys Vlasenko <dvlasenk@...hat.com>, Oleg Nesterov <oleg@...hat.com>, Dave Hansen <dave@...1.net> Subject: Re: [all better] Re: regression: massive trouble with fpu rework * H. Peter Anvin <hpa@...or.com> wrote: > On 06/28/2015 11:40 PM, Ingo Molnar wrote: > > > > Ok, so could you please move the fpu__init_system() further up and see which > > position is that starts breaking with the BIOS option set? > > > > here's the current, broken layout of the code: > > > > get_cpu_cap(c); > > [0] fpu__init_system(c); > > > > if (this_cpu->c_early_init) > > this_cpu->c_early_init(c); > > > > [1] > > c->cpu_index = 0; > > [2] > > filter_cpuid_features(c, false); > > > > [3] > > if (this_cpu->c_bsp_init) > > this_cpu->c_bsp_init(c); > > > > [4] > > setup_force_cpu_cap(X86_FEATURE_ALWAYS); > > [5] > > } > > > > and we know it from your testing that moving [0] to [5] fixes the crash. > > > > The question is, can we move it to [4], [3], [2] or even [1] instead, without > > breaking the system? > > > > I still don't see where the breakage comes from, but this would help us narrow it > > down. > > > > It should be moved to [4] or [5]. I would argue that the line setting > X86_FEATURE_ALWAYS should moved up and then fpu__init_system(c) should > be moved after the c_bsp_init() line. Yeah, so the patch I sent to Mike (and which solved the bug) moved it to [5]. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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