Messages in this thread | | | Date | Mon, 8 Aug 2011 17:08:07 +0800 | Subject | Re: powertop "pread cpu0 0xe8 : Bad file descriptor" fixed by CONFIG_MSR | From | Américo Wang <> |
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On Sun, Aug 7, 2011 at 6:52 AM, Andy Isaacson <adi@hexapodia.org> wrote: > I hadn't seen this issue discussed on the list, and I don't know of a > powertop mailing list, so here's what stymied my use of powertop until I > straced it. > > With CONFIG_MSR=n, powertop "1.97-2" (from Debian unstable) on 3.0.1 > (and presumably many other recent kernels) exits at startup with: > > pread cpu0 0xe8 : Bad file descriptor > > strace shows: > > open("/dev/cpu/0/msr", O_RDONLY) = -1 ENOENT (No such file or directory) > pread(4294967295, 0x7fff4c8347c8, 8, 232) = -1 EBADF (Bad file descriptor) >
Seems powertop forgot to check the return value of that open(). This is a bug of powertop, not kernel.
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