Messages in this thread | | | Date | Tue, 15 Jan 2008 19:44:24 +0100 | From | Jan Kiszka <> | Subject | Re: State of kgdb on x86-64 |
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Jason Wessel wrote: > Jan Kiszka wrote: >> Jason Wessel wrote: >> >>> It was working at the point that I tested it with the 2.6.24-rc5 on >>> x86_64. However I suspect my kernel config may differ drastically from >>> what you are using. >>> >>> Without any other context provided than the generic message, it is hard >>> to know what might have happened. >>> >> Here is the promised .config. I could also dig out the backtrace of the >> panic as kgdb sees it if that helps, just let me know. >> >> Jan >> >> > The backtrace might be very telling as to what happened. More > information is always better than less :-) >
My primary test box is again out of reach, but meanwhile I was able to reproduce some kind of problem under QEMU - that one at least is triggered by SMP. With only one CPU -> all apparently fine. Once booting QEMU with "-smp 2" -> this happens:
(gdb) tar remote /dev/pts/6 Remote debugging using /dev/pts/6 Not all CPUs have been synced for KGDB breakpoint () at kernel/kgdb.c:1895 1895 wmb(); /* Sync point after breakpoint */ (gdb) c Continuing. Not all CPUs have been synced for KGDB [New Thread 32769]
Program received signal SIGFPE, Arithmetic exception. [Switching to Thread 32769] 0xffffffff8020adb7 in default_idle () at include/asm/irqflags_64.h:140 140 __asm__ __volatile__("sti; hlt" : : : "memory"); (gdb) bt #0 0xffffffff8020adb7 in default_idle () at include/asm/irqflags_64.h:140 #1 0xffffffff8020ae65 in cpu_idle () at arch/x86/kernel/process_64.c:225 #2 0xffffffff8021ccb9 in start_secondary () at arch/x86/kernel/smpboot_64.c:375 #3 0x0000000000000000 in ?? () (gdb)
The problem seems to be related to continuing SMP boxes. I'm able to boot my box up if I leave kgdb unattached. But when I then later attach and continue execution, I get the same crash. Any ideas what goes wrong, any suggestion where to start digging? Maybe at "Not all CPUs have been synched"?
Jan
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