Date: Wed, 20 Dec 2006 12:41:47 -0800 From: "Kip Macy" <kip.macy@gmail.com> To: "Dmitry Pryanishnikov" <dmitry@atlantis.dp.ua> Cc: Kostik Belousov <kostikbel@gmail.com>, freebsd-current@freebsd.org, Kip Macy <kmacy@freebsd.org> Subject: Re: ddb(4) spoils kernel stack in CURRENT? Message-ID: <b1fa29170612201241t3de56acag81d60348a07a1791@mail.gmail.com> In-Reply-To: <20061220215753.H53808@atlantis.atlantis.dp.ua> References: <20061219175917.L84683@atlantis.atlantis.dp.ua> <20061220130559.P54963@atlantis.atlantis.dp.ua> <20061220124032.GC23698@deviant.kiev.zoral.com.ua> <20061220215753.H53808@atlantis.atlantis.dp.ua>
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I worried that gdb probably had workaround for the large stack argument. I'll have to dig it up, thanks for the heads up. -Kip On 12/20/06, Dmitry Pryanishnikov <dmitry@atlantis.dp.ua> wrote: > > > Hello! > > On Wed, 20 Dec 2006, Kostik Belousov wrote: > >>> So it looks like a regression in CURRENT vs RELENG_6 (either ddb > 'spoils' > >>> the stack somehow, or kgdb fails to unwind it). > > > > Could you further localize the problem, i.e. try to backtrace CURRENT > dump > > Good news: I've managed to localize the bug! I'm Feeling Lucky (TM) ;) > just because CURRENT on my notebook was updated approx. at 17-Dec 00:00, > and it didn't manifest such a behaviour! So it was easy to identify the > regression - it comes with the following commit: > > ----------------------------------------------------------------------- > > Date: Sun, 17 Dec 2006 05:07:01 +0000 (UTC) > From: Kip Macy <kmacy@freebsd.org> > To: src-committers@freebsd.org, cvs-src@freebsd.org, cvs-all@freebsd.org > Subject: cvs commit: src/sys/i386/i386 apic_vector.s exception.slocal_apic.c > trap.c vm86.c vm86bios.s src/sys/i386/include apicvar.h > src/sys/i386/isa atpic.c atpic_vector.s icu.h > > kmacy 2006-12-17 05:07:01 UTC > > FreeBSD src repository > > Modified files: > sys/i386/i386 apic_vector.s exception.s local_apic.c > trap.c vm86.c vm86bios.s > sys/i386/include apicvar.h > sys/i386/isa atpic.c atpic_vector.s icu.h > Log: > Evidently FreeBSD has long relied on the compiler to treat structures > passed by value (trap frames) as if they were in fact being passed by > reference. For better or worse, this incorrect behaviour is no longer > present in gcc 4.1. In this patch I convert all trapframe arguments to > be explicitly pass by reference. I also remove vm86_initflags, pushing > the very little work that it actually does up into vm86_prepcall. > > ----------------------------------------------------------------------- > > So kernel built from sources as of date=2006.12.17.05.00.00 gives dump > with analyzable backtrace, and kernel built from sources as of > date=2006.12.17.05.10.00 (which include this commit) gives dump > which confuses kgdb. I believe that commit itself is correct, > but kgdb contains some workaround against the old (incorrect) behaviour > of the kernel, so it's the kgdb that should be fixed. > > Sincerely, Dmitry > -- > Atlantis ISP, System Administrator > e-mail: dmitry@atlantis.dp.ua > nic-hdl: LYNX-RIPE > _______________________________________________ > freebsd-current@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org" >
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