Date: Thu, 26 Mar 2009 09:38:39 -0700 From: Nate Lawson <nate@root.org> To: "Stephane E. Potvin" <sepotvin@FreeBSD.org> Cc: freebsd-acpi@FreeBSD.org, Andriy Gapon <avg@icyb.net.ua> Subject: Re: kern/108581: [sysctl] sysctl: hw.acpi.cpu.cx_lowest: Invalid argument Message-ID: <49CBAF8F.9080301@root.org> In-Reply-To: <49CBA1E5.2090902@FreeBSD.org> References: <200903200030.n2K0U3iG011009@freefall.freebsd.org> <20090325223914.4387eeae@gluon.draftnet> <49CB8C86.4020800@icyb.net.ua> <20090326142832.0dba187a@gluon.draftnet> <49CB9224.6010509@icyb.net.ua> <20090326144140.2203c0d8@gluon.draftnet> <49CB9973.3010306@icyb.net.ua> <20090326151035.51e4196e@gluon.draftnet> <49CB9C1B.4070308@icyb.net.ua> <49CBA1E5.2090902@FreeBSD.org>
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Stephane E. Potvin wrote: > Andriy Gapon wrote: >> on 26/03/2009 17:10 Bruce Cran said the following: >>> On Thu, 26 Mar 2009 17:04:19 +0200 >>> Andriy Gapon <avg@icyb.net.ua> wrote: >>> >>>> on 26/03/2009 16:41 Bruce Cran said the following: >>>>> I added lots of printfs to acpi_cpu.c and found that it's occuring >>>>> in acpi_cpu_startup; initializing it to 3 in that function (which I >>>>> wrongly assumed was the lowest Cx state supported in ACPI) fixed >>>>> the problem on my Athlon XP PC because the generic cx handling code >>>>> then lowered cpu_cx_count to 1 based on the fact that >>>>> sc->cpu_cx_count was also 1. >>>>> >>>> Ok, yes, the real issue is in acpi_cpu_generic_cx_probe, namely in >>>> early exits from it. So, sc->cpu_cx_count is always set to at least >>>> 1, but if we exit via one of the returns before the end of function, >>>> then global cpu_cx_count is never updated. >>>> >>> Exactly: >>> >>> acpi: acpi_cpu_startup: initializing cpu_cx_count to 0 >>> acpi_cpu_generic_cx_probe >>> if sc->cpu_p_blk_len < 5 [sc->cpu_p_blk_len = 0] >>> acpi: acpi_cpu_startup: cpu 0,cpu_cx_count = 0,sc->cpu_cx_count = 1 >>> >>> So we're hitting an early exit in acpi_cpu_generic_cx_probe. >>> >> John, what would be a better fix - initialize the global variable to 1 or use goto >> in acpi_cpu_generic_cx_probe? >> I think the latter is more consistent and obvious, the former is simpler and >> safer, though. >> > > Your right, it seems that I need to order some more pointy hats. There > should have been a goto there to jump at the end in order to initialize > the global cpu_cx_count. The following patch should fix your issue. > John, is this ok with you? John's patch does the same thing without a goto (see message <200903261129.50419.jhb@freebsd.org>) -- Nate
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