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Re: [Qemu-discuss] aarch64 ivshmem issues

From: Meng Xu
Subject: Re: [Qemu-discuss] aarch64 ivshmem issues
Date: Sun, 10 Jan 2016 18:12:25 -0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0

Hi Peter,

Thank you for the reply.

I removed the highmem=off option and the result is the same. Plus,
I could not see the ivshmem device when I do `lshw` in the guest in
either configuration.

I'll try to build the kernel with PCI diagnostic config to see if there are
more info. Thank you for the advice!

Best Regards,

On 01/10/2016 06:06 PM, Peter Maydell wrote:
On 10 January 2016 at 13:07, Meng Xu <address@hidden> wrote:
Hi All,

I am using the ivshmem device to create shared memory between an x86_64 host 
and aarch64 guest.
The guest has ubuntu server 14.04 installed with kernel version 3.13.0. I wrote 
a kernel driver to
drive the ivshmem device (as a pci driver) however, the driver was never 

Can anyone help me point out what is wrong?

My qemu launch script looks like this:
qemu-system-aarch64 -machine virt,highmem=off -cpu cortex-a57 -m 1024M \
         -drive file=<path-to-img>,id=hd0,if=none,format=qcow2 \
         -device virtio-blk-device,drive=hd0 \
         -device ivshmem,shm=vshmtest,size=16M \
         -kernel <path-to-kernel> \
         -initrd <path-to-initrd> \
You're using "highmem=off", which is disabling the
high-address PCI window. That means that PCI devices
which want a large address range for their PCI BARs
won't work. I think that ivshmem is one such device
(and in fact ivshmem is the reason we added the high

Is there a reason why you have this in your command line?

I would expect that if you've built your kernel with
the relevant PCI diagnostic config options enabled,
the kernel should print out as it boots the PCI cards
it sees and what it's doing with them. That ought to
help in trying to diagnose what's happening.

-- PMM

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