Date: Fri, 29 Feb 2008 02:24:35 +0300 From: Yuri Pankov <yuri.pankov@gmail.com> To: freebsd-emulation@freebsd.org Subject: Re: qemu-system-amd64 and freebsd guest Message-ID: <20080228232434.GA1562@mail.irbisnet.ru> In-Reply-To: <20080216181850.GA35839@saturn.kn-bremen.de> References: <20080216164331.GJ57756@deviant.kiev.zoral.com.ua> <20080216181850.GA35839@saturn.kn-bremen.de>
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On Sat, Feb 16, 2008 at 07:18:50PM +0100, Juergen Lock wrote:
> On Sat, Feb 16, 2008 at 06:43:31PM +0200, Kostik Belousov wrote:
> > My recent attempts to boot CURRENT amd64 on QEMU 0.9.1 resulted in the
> > consistent kernel panic in the first instruction of the root_bus_ocnfigure()
> > function. Looking around, I noted that this instruction is the second one
> > executed after "sti" in the amd64/amd64/autoconf.c:configure().
> > CPU executes
> > sti
> > call root_bus_configure
> > pushq %rbp <- General Protection Fault there
> >
> > It makes me suspect that fault happen when hardware interrupt is delivered.
> > Indeed, looking around qemu source code and setting breakpoints in QEMU,
> > I noted that hw interrupt is delivered, with into = -1. Calculation of
> > the IDT index in the QEMU' target-i386/helper.c:do_interrupt64() as
> > intno*16 and comparision with unsigned limit looked as overflow and GPF
> > was delivered instead.
> >
> > Then, it appears that -1 comes from cpu_get_pic_interrupt() when
> > apic_accept_pic_intr() returns false. This happen, in particular, when
> > corresponding lapic vector is masked. The situation is legitimate, and
> > I think that QEMU shall not deliver an interrupt in this case.
> >
> > The following patch allows me to boot the amd64 freebsd on qemu 0.9.1
> > from ports.
> >
> > --- cpu-exec.c.orig 2008-02-16 18:23:53.134009488 +0200
> > +++ cpu-exec.c 2008-02-16 18:24:47.127662872 +0200
> > @@ -452,13 +452,15 @@
> > svm_check_intercept(SVM_EXIT_INTR);
> > env->interrupt_request &= ~(CPU_INTERRUPT_HARD | CPU_INTERRUPT_VIRQ);
> > intno = cpu_get_pic_interrupt(env);
> > - if (loglevel & CPU_LOG_TB_IN_ASM) {
> > - fprintf(logfile, "Servicing hardware INT=0x%02x\n", intno);
> > - }
> > - do_interrupt(intno, 0, 0, 0, 1);
> > - /* ensure that no TB jump will be modified as
> > - the program flow was changed */
> > - BREAK_CHAIN;
> > + if (intno != -1) {
> > + if (loglevel & CPU_LOG_TB_IN_ASM) {
> > + fprintf(logfile, "Servicing hardware INT=0x%02x\n", intno);
> > + }
> > + do_interrupt(intno, 0, 0, 0, 1);
> > + /* ensure that no TB jump will be modified as
> > + the program flow was changed */
> > + BREAK_CHAIN;
> > + }
> > #if !defined(CONFIG_USER_ONLY)
> > } else if ((interrupt_request & CPU_INTERRUPT_VIRQ) &&
> > (env->eflags & IF_MASK) && !(env->hflags & HF_INHIBIT_IRQ_MASK)) {
>
> Hey, thanks for looking at this one! :) Maybe you should post the patch
> on the qemu list so the right ppl can look at it, and see if it is correct:
> http://lists.gnu.org/mailman/listinfo/qemu-devel
>
> Thanx,
> Juergen
Thanks from me too. I was finally able to boot 7.0-bootonly amd64 image
inside QEMU with this patch :-)
Yuri
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