Date: Wed, 8 Jul 2009 12:40:19 +0100 From: Anton Shterenlikht <mexas@bristol.ac.uk> To: Marcel Moolenaar <xcllnt@mac.com> Cc: Rink Springer <rink@freebsd.org>, Anton Shterenlikht <mexas@bristol.ac.uk>, freebsd-current@freebsd.org, freebsd-ia64@freebsd.org Subject: Re: buildworld panic on ia64 Message-ID: <20090708114019.GA19781@mech-cluster238.men.bris.ac.uk> In-Reply-To: <93B562A8-9FE7-44D5-91E4-C9AB1A25BD2A@mac.com> References: <20090707094808.GA93317@mech-cluster238.men.bris.ac.uk> <20090707095058.GC7827@rink.nu> <20090707124405.GA46091@mech-cluster238.men.bris.ac.uk> <20090707133611.GA66072@rink.nu> <93B562A8-9FE7-44D5-91E4-C9AB1A25BD2A@mac.com>
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On Tue, Jul 07, 2009 at 05:29:06PM -0700, Marcel Moolenaar wrote: > > On Jul 7, 2009, at 6:36 AM, Rink Springer wrote: > >> I tried to reproduce the error, got this on the way: > >> > >> # XXX: bogusly disabled high FP regs > > > > I get this message quite often as well; I intend to figure out what's > > going on. Marcel, if you have any idea, please let me know. > > It's a race condition. The high FP registers are lazily > context-switched and this error is emitted when a thread > wants to use the high FP registers when they are disabled > and the CPU onto which the thread is running has the high > FP registers corresponding to that thread in registers. > In that scenario the high FP registers should not even be > disabled. > > In the above case the kernel simply enables the high FP > registers and continues the thread. For the most part the > condition is harmless, but I've been looking at a panic > that's the result of inconsistency in the high FP state, > so the race is potentially fatal. > > BTW: I never got the error when doing a buildworld. I > think Anton's non-standard compiler options make GCC much > more FP intensive and thus prone to causing the race. hey, my compiler options are just a copy from /usr/share/examples/etc/make.conf with obvious changes, e.g. CPUTYPE=itanium2 The CFLAGS, COPTFLAGS, CXXFLAGS are as in the example make.conf. Which non-standard options did you spot? -- Anton Shterenlikht Room 2.6, Queen's Building Mech Eng Dept Bristol University University Walk, Bristol BS8 1TR, UK Tel: +44 (0)117 928 8233 Fax: +44 (0)117 929 4423
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