----------------------------------------
> Date: Wed, 3 Mar 2010 15:09:17 -0700
> Subject: Re: IVSHMEM and limits on shared memory
> From: c...@cs.ualberta.ca
> To: kz...@hotmail.com
> CC: kvm@vger.kernel.org
>
> On Wed, Mar 3, 2010 at 12:06 AM, Khaled Ibrahim wrote:
>>
>> Hi Cam,
>>
>> I used your patches successfully to support shared memory on KVM and
>> used the test cases successfully, but qemu-kvm crashes when I increased the
>> size of the shared memory. I
>> applied the ivshmem patch to qemu-kvm-0.12.3 (some manual patching was
>> needed). It worked flawlessly for
>> up to 128MB of shared memory on my system. I am running on a machine with
>> 64GB
>> memory running opensuse (kernel 2.6.27) on AMD opteron.
>>
>> Qemu crashes with
>> smp=4 and the shared memory requested in 256MB, (512MB with smp=1), even
>> though
>> the shared memory file is created. I debugged the problem and it seems that
>> some memory corruptions happens.
>
> Can you please provide the full command-line for the smp=1 instance?
qemu-system-x86_64 ./qemudisk0.raw \ -net
nic,model=rtl8139,macaddr=52:54:00:12:34:50\ -net
tap,ifname=tap0,script=no,downscript=no \ -m 4096 \ -ivshmem
512,kvmshmem\ -smp 1 \ -usb \ -usbdevice tablet \
-localtime
>
>>
>> It crashes in the subpage_register for rtl8139 pci driver!,
>> tracked back to rtl8139_mmio_map. The problem starts with corrupted value in
>> the config field in the struct for the rtl8139 driver. At offset 20 of this
>> field the address should indicate that the address is uninitialized at that
>> time of crash, but surprisingly the value changes over the course of
>> execution
>> and gets the SIZE of the shared memory allocated (related to ivshmem). I
>> failed
>> to identify what changes/corrupts that field. I tried some padding for
>> allocation but the field always gets updated with the size of the shared
>> memory
>> in a very consistent way.
>>
>
> As far as you know does anything in the guest trigger the corruption?
> Does the corruption happen immediately or after running some of the
> test programs?
The boot process does not complete, and it fails before it reach grub.
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