Re: [Qemu-ppc] Adding canyonlands/460EX support to QEMU in qemu-system-ppc

[Allen Kneser]

Hi Alexander,

Thank you for your help! This is quite useful!

Pardon my lack of expertise, but what do you mean by KVM being available for canyonlands? I am actually trying to emulate this PowerPC board on an x86_64 PC, and my understanding is that I cannot benefit from KVM virtualization in this setup because of the architecture difference. 

On a related note, my performance is not great at all:

QEMU bamboo sysbench CPU test:

      total time:                          10.3413s

      total number of events:              9

      total time taken by event execution: 10.2956

AMCC canyonlands sysbench CPU test:

      total time:                          10.0043s

      total number of events:              621

      total time taken by event execution: 10.0032

Core 2 Duo P8700 @ 2.53Ghz sysbench CPU test:

      total time:                          9.6486s

      total number of events:              10000

      total time taken by event execution: 9.6338

Is this to be expected? Would you have any suggestions on how to improve performance? 

Would adding the 460EX with FP CPU to QEMU improve performance?
Would the performance increase drastically by running the VM on a PowerPC machine with KVM support on the host and the guest?

--Allen

On Mon, Feb 25, 2013 at 6:53 AM, Alexander Graf <address@hidden> wrote:

Hi Allen,

On 20.02.2013, at 06:10, Allen Kneser wrote:

> Hi,
>
> I downloaded and compiled the QEMU 1.4.0 sources, wanting to emulate an AMCC canyonlands PowerPC board (http://www.apm.com/products/embedded/singlecore460/ppc460ex). I am running my own Linux distro on this board with a custom-built kernel and ramdisk. I am in need of a "virtual testbed" that resembles this board, so I can install the same kernel and ramdisk that are on the board on the virtual testbed.
>
> While running 'qemu-system-ppc -M ?', I noticed that canyonlands is not one of the options there and, also 460EX is not among the supported CPUs in 'qemu-system-ppc -cpu ?'. I have tried booting my kernel and ramdisk with the other -M options but had no luck.
>
> I am relatively new to QEMU, so I might be on the wrong track here, but I am wondering if, in order to create a QEMU VM that resembles the canyonlands board, there are certain qemu-system-ppc arguments/parameters that escape me right now, or if I need to modify QEMU and add support for canyonlands, just like there is support for, say AMCC taihu, in qemu/hw/ppc405_boards.c

Well, the closest board to the canyonlands is hw/ppc440_bamboo.c. But yes, you would need to create a board file similar to that for the canyonlands and also add a CPU definition for the 460EX core.

> If I need to modify QEMU, I would appreciate any advice on whether adding canyonlands support is possible given the QEMU architecture and perhaps a few tips on what would need to be done.

It is certainly possible and shouldn't be very hard to do so. The canyonland is very close to bamboo. Just copy the bamboo board, change the device locations to what your canyonland board has, use the canyonland device tree and check where it breaks :). For starters, I'd probably start booting with -cpu 440EP or -cpu 440GP (depending on whether you have floating point) to not get into the core emulation trouble.

Also, did you know that there is kvm available for your board? I am very close to ripping it out of the kernel because there are no users, but if I hear about any, I wouldn't object to keeping it in.


Alex