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    SubjectRe: [Bug #13116] Can't boot with nosmp
    Dan Williams wrote:
    > On Mon, Jun 8, 2009 at 5:04 PM, Stephen Hemminger<shemminger@vyatta.com> wrote:
    >
    >> I did some more debugging, and the problem appears to be that
    >> booting with nosmp still leaves all the CPU's present in the cpu
    >> possible mask. So code like dma engine (or loopback device), that
    >> use alloc_percpu get broken.
    >>
    >> Not sure why all the cpu's are still showing up in the possible mask.
    >> Rusty? do you have an answer.
    >>
    >
    > Would this recent commit also fix this issue?
    >
    > commit a4c0364be3f43d3e17fe19270f8b3d64881606e6
    > Author: Avi Kivity <avi@redhat.com>
    > Date: Sat Jun 6 12:34:39 2009 +0300
    >
    > KVM: Explicity initialize cpus_hardware_enabled
    >
    > Under CONFIG_MAXSMP, cpus_hardware_enabled is allocated from the heap and
    > not statically initialized. This causes a crash on reboot when kvm thinks
    > vmx is enabled on random nonexistent cpus and accesses nonexistent percpu
    > lists.
    >
    > Fix by explicitly clearing the variable.
    >
    > Cc: stable@kernel.org
    > Reported-and-tested-by: Yinghai Lu <yinghai@kernel.org>
    > Signed-off-by: Avi Kivity <avi@redhat.com>
    >

    This only affects reboots. But yes, the cpumask code has bugs. Does
    the .config involved select MAXSMP?

    --
    I have a truly marvellous patch that fixes the bug which this
    signature is too narrow to contain.



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