Re: [Qemu-devel] [PATCH 00/11] S390x KVM support v4

[Aurelien Jarno <aurelien@aurel32.net>]

Hi,

On Thu, Nov 26, 2009 at 02:23:09PM +0100, Alexander Graf wrote:
> While S390x was one of the first targets that were supported by KVM it always
> lacked qemu system emulation support.
> 
> In order to change that sad fact, I figured I'd just take on the task myself,
> taking kuli (http://www.ibm.com/developerworks/linux/linux390/kuli.html),
> Documentation/s390/kvm.txt and lguest as starting points to write a clean,
> qemu'ish S390x Virtio machine emulation.
> 
> So now you can run Linux VMs on Linux on z/VM on LPAR on zSeries!
> 
> This is the resulting code. Please comment on things you like and also on the
> ones you don't :-).
> 
> The patchset is based on Uli's S390x userspace emulation patches. There's not
> really that much shared functionality, but I didn't want to reimplement the
> configure wheels. So make sure to have his patches applied first.
> 
> Please only run S390x system virtualization using io threads. S390x has very
> few intercepts and even less that actually reach userspace. So you'll end up
> with a non-responsive VM without a dedicated IO thread.
> 
> Use: $ ./configure --target-list=s390x-softmmu --enable-io-thread
> 
> Currently only -kernel, -initrd and friends work. Booting from a real dasd
> device is not supported.
> 
> Also to actually run this code you need a patch for an ugly bug in the kernel
> module that Carsten sent a patch to on the ML.
> 
> I verified that the userspace actually works on a 2.6.27 (SLES11) kernel, so
> if it doesn't work on current git, please tell me! I'm too afraid that I might
> end up in a 3270 terminal to update the kernel on my z/VM instance :-).
> 
> ##### WARNING #####
> 
> Apparently the qemu review process has scared off yet another developer for now.
> 
> So I'm sending this patchset without relying on Uli's set but rather
> implemented small stubs for TCG host and TCG guest support, so we can run
> on KVM. He promised me to send it again "soon" - whenever that is.
> 
> These stubs don't serve any purpose but to get KVM running, so you get no x86
> on S390X or S390X on x86 for now!
> 

This patchset basically looks ok. I have some minor comments, a lot of
them being related to coding style, but they should be easy to solve,
and should not prevent inclusion in 0.12.0 release.

Please find comments in the individual patches.

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net