Messages in this thread Patch in this message | | | Date | Tue, 9 Sep 2003 22:31:32 +0200 (MEST) | From | Mikael Pettersson <> | Subject | Re: PROBLEM: APIC on a Pentium Classic SMP, 2.4.21-pre2 and 2.4.21-pre3 ksymoops |
| |
On Mon, 08 Sep 2003 19:22:17 -0400, Mathieu Desnoyers wrote: >> >On kernel 2.4.21-pre2, there is a kernel oops before this, with a >> >"Dereferencing NULL pointer". >> >> You didn't run that through ksymoops and post it, so how is anyone >> supposed to be able to debug it? > >As only 2.4.21-pre2 and 2.4.21-pre3 kernels show this problem, I thought >it has been corrected in 2.4.21-pre4. But, as it can be very useful in >finding the problem, here are the ksymoops for 2.4.21-pre2 and >2.4.21-pre3 kernels, quite similar though. ... >Code; c0115da7 <IO_APIC_get_PCI_irq_vector+17/130> >00000000 <_EIP>: >Code; c0115da7 <IO_APIC_get_PCI_irq_vector+17/130> <===== > 0: 83 3c 90 ff cmpl $0xffffffff,(%eax,%edx,4) <=====
Ok, that one is line 295 in io_apic.c. It bombs in 2.4.21-pre{2,3} because mp_bus_id_to_pci_bus was changed from a static array to a dynamically allocated array. On your machine, smp_read_mpc() in mpparse.c doesn't get to the point where it allocates that array, so the array is NULL in io_apic.c and you get an oops.
Fixing the oops is easy (see below), but the real problem is that 2.4.21-pre2 apparently broke MP table parsing on your HW. I suggest you sprinkle tracing printk()s in setup/smpboot/mpparse and compare 2.4.20 (good) and later (bad) to see where things start to diverge.
/Mikael
--- linux-2.4.21-pre2/arch/i386/kernel/io_apic.c.~1~ 2003-09-09 21:27:39.000000000 +0200 +++ linux-2.4.21-pre2/arch/i386/kernel/io_apic.c 2003-09-09 22:17:02.464082064 +0200 @@ -292,7 +292,7 @@ Dprintk("querying PCI -> IRQ mapping bus:%d, slot:%d, pin:%d.\n", bus, slot, pin); - if (mp_bus_id_to_pci_bus[bus] == -1) { + if ((mp_bus_id_to_pci_bus==NULL) || mp_bus_id_to_pci_bus[bus] == -1) { printk(KERN_WARNING "PCI BIOS passed nonexistent PCI bus %d!\n", bus); return -1; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |