Messages in this thread | | | From | Ondrej Zary <> | Subject | Debugging APM - cat /proc/apm produces oops | Date | Sun, 23 Jul 2006 16:30:53 +0200 |
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Hello, cat /proc/apm produces oops on my DTK notebook. Using "apm=broken-psr" kernel parameter fixes that but I lose the battery info. I'd like to have the battery info (and it works fine in Windows) so I want to debug it and (hopefully) fix.
The oops: # cat /proc/apm <1>BUG: unable to handle kernel paging request at virtual address 00005e88 printing eip: 00002f9d *pre = 00000000 Oops: 0002 [#4] Modules linked in: CPU: 0 EIP: 00c0:[<00002f9d>] Not tainted VLI EFLAGS: 00010017 (2.6.17-5-dtk #23) EIP is at 0x2f94 eax: 00000033 ebx: 00000001 ecx: 00000000 edx: 00000000 esi: c10a1000 edi: 00000014 ebp: c4755e8a esp: c4755e88 ds: 00c8 es: 0000 ss: 0068 Process cat (pid: 1928, threadinfo=c4754000 task=c11240b0) Stack: 5e948001 5fc75e55 00005e94 000000c8 10000033 5ea800c0 00000001 530a0000 00000016 00b86017 00000000 0000530a c010830f 00000060 0000530a 00000033 0000007b 0000007b c0337368 00000000 c10a1000 00000000 00000000 00000282 Call Trace: <c010830f> apm_bios_call+0x68/0xba <c0108728> apm_get_power_status+0x44/0x90 <c01091a0> apm_get_info+0x34/0xdc <c01617dc> proc_file_read+0xda/0x22d <c013b5a2> vfs_read+0x82/0x10e <c013b873> sys_read+0x3c/0x62 <c0102397> syscall_call+0x7/0xb Code: Bad EIP value. EIP: [<00002f9d>] 0x2f9d SS:ESP 0068:c4755e88
So it looks like it dies somewhere in the APM BIOS code. But how to find exactly where and/or why? Maybe use GDB somehow (I've used it only for really simple debugging yet). I've tried calling the APM 0x530A function from DOS (real mode, int 15h) and single-stepping the BIOS APM code (using good old user-friendly Turbo Debugger). Noticed some OUTs to 0xB1 (or something like that), then some PCI accesses (0xCF8 and 0xCFC) and then IP ended in area of all zeros. When I step over the int 15h call, it works fine - returns correct info.
-- Ondrej Zary - 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/
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