On Thu, Mar 01, 2007 at 11:12:42PM +0000, Sean Young wrote: > Apologies if this has already been reported. > > If I call clock_gettime(CLOCK_THREAD_CPUTIME_ID, .. ) twice I get: > > divide error: 0000 [#1] > Modules linked in: binfmt_misc rfcomm l2cap bluetooth sonypi speedstep_ich > speedstep_lib cpufreq_userspace cpufreq_stats cpufreq_powersave > cpufreq_ondemand freq_table cpufreq_conservative video thermal sbs processor > i2c_ec fan dock button battery ac af_packet ipv6 sbp2 lp usb_storage libusual > orinoco_cs orinoco hermes joydev tsdev usbhid pcmcia e100 mii psmouse > ohci1394 serio_raw yenta_socket rsrc_nonstatic pcmcia_core ieee1394 sr_mod > cdrom sg uhci_hcd parport_pc parport pcspkr evdev usbcore > CPU: 0 > EIP: 0060:[<c0126a07>] Not tainted VLI > EFLAGS: 00010246 (2.6.21-rc2 #1) > EIP is at sample_to_timespec+0x28/0x33 > eax: 63b5a669 ebx: fffffffa ecx: 63b5a669 edx: fffffffa > esi: d4a56fa4 edi: 3b9aca00 ebp: d4a56fa4 esp: d4a56f74 > ds: 007b es: 007b fs: 00d8 gs: 0033 ss: 0068 > Process x (pid: 3894, ti=d4a56000 task=dfe9aa50 task.ti=d4a56000) > Stack: 00000000 fffffffe 00000000 c0127d49 d4a56fa4 63b5a669 fffffffa fffffffe > 00000003 00000000 d4a56000 c0125bf3 b7f68ff4 b7f9fce0 fffffffe 00000003 > c0103bfc fffffffe bfd6d5d8 b7f74ff4 00000003 00000000 bfd6d5b8 00000109 > Call Trace: > [<c0127d49>] posix_cpu_clock_get+0x47/0xdc > [<c0125bf3>] sys_clock_gettime+0x80/0x82 > [<c0103bfc>] syscall_call+0x7/0xb > [<c02f0000>] svc_ioctl+0xc2/0x261 > ======================= > Code: 0b eb fe 57 56 53 89 cb 89 d1 8b 74 24 10 83 e0 03 83 f8 02 74 0c 89 f2 > 89 c8 5b 5e 5f e9 ee 3f ff ff bf 00 ca 9a 3b 89 d0 89 da <f7> f7 89 56 04 89 > 06 5b 5e 5f c3 55 57 56 53 89 c7 89 d6 89 cb > EIP: [<c0126a07>] sample_to_timespec+0x28/0x33 SS:ESP 0068:d4a56f74 > > The instruction is: > > div %edi > > And edi is 1e9 (0x3b9aca00). I don't understand why this results in an > divide error.
It does this because 'div' does an unsigned divide of edx:eax by edi. Here, edx=fffffffa and eax is 63b5a669. Clearly, such a number cannot be divided by 1e9 to return a 32 bits value. Given the values we see here, I suspect the code should have used an integer divide (idiv). This means that something in the code implies that the result is unsigned while it should be signed. Regards, Willy - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
