Date: Fri, 12 Nov 2010 17:15:57 -0800 From: Colin Percival <cperciva@freebsd.org> To: "freebsd-xen@freebsd.org" <freebsd-xen@freebsd.org> Cc: mav@freebsd.org Subject: DomU panic during boot with recent timer changes (+ workaround) Message-ID: <4CDDE6CD.3010606@freebsd.org>
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Hi all, Following mav's timer refactoring (r212541) I'm seeing a panic during boot: > Fatal trap 1: privileged instruction fault while in kernel mode > cpuid = 0; apic id = 00 > instruction pointer = 0x21:0xc031ac5c > stack pointer = 0x29:0xc2719c84 > frame pointer = 0x29:0xc2719c88 > code segment = base 0x0, limit 0xf9800, type 0x1b > = DPL 1, pres 1, def32 1, gran 1 > processor eflags = interrupt enabled, resume, IOPL = 0 > current process = 11 (idle: cpu0) > trap number = 1 > panic: privileged instruction fault > cpuid = 0 > KDB: stack backtrace: > #0 0xc0106057 at kdb_backtrace+0x47 > #1 0xc00d3c47 at panic+0x117 > #2 0xc032efa3 at dblfault_handler+0x3c3 > #3 0xc032f8ad at trap+0x5ed > #4 0xc03150bb at alltraps+0x1b > #5 0xc031acb0 at cpu_idle+0x30 > #6 0xc00f9133 at sched_idletd+0x263 > #7 0xc00aa7a8 at fork_exit+0xb8 > #8 0xc0315134 at fork_trampoline+0x8 > Uptime: 1s It looks like the privileged instruction fault is being triggered by mwait. Setting machdep.idle_mwait=0 prevents this panic; I'm not sure if Xen is supposed to handle mwait or not, so I don't know if mwait should be disabled unconditionally for Xen/PV kernels, but maybe someone here knows more than I do. :-) -- Colin Percival Security Officer, FreeBSD | freebsd.org | The power to serve Founder / author, Tarsnap | tarsnap.com | Online backups for the truly paranoid
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