Re: [Qemu-devel] [PATCH 05/17] kvm: add kvm stub for arch specific stuff

[Alexander Graf]

On 03.05.2011, at 16:57, Jan Kiszka wrote:

> On 2011-05-03 16:17, Alexander Graf wrote:
>> 
>> On 18.04.2011, at 20:34, Aurelien Jarno wrote:
>> 
>>> On Fri, Apr 15, 2011 at 05:32:46PM +0200, Alexander Graf wrote:
>>>> We have a generic stub architecture for kvm calls, but some architectures
>>>> are different from others. So we do want to be able to have stubs for
>>>> architecture specific functionality as well.
>>>> 
>>>> This patch adds kvm stubs for all architectures.
>>>> 
>>>> Signed-off-by: Alexander Graf <address@hidden>
>>>> ---
>>>> Makefile.target                   |    2 +-
>>>> target-alpha/kvm-arch-stub.c      |   26 +++++++++++++++++++++++++
>>>> target-arm/kvm-arch-stub.c        |   26 +++++++++++++++++++++++++
>>>> target-cris/kvm-arch-stub.c       |   26 +++++++++++++++++++++++++
>>>> target-i386/kvm-arch-stub.c       |   26 +++++++++++++++++++++++++
>>>> target-lm32/kvm-arch-stub.c       |   26 +++++++++++++++++++++++++
>>>> target-m68k/kvm-arch-stub.c       |   26 +++++++++++++++++++++++++
>>>> target-microblaze/kvm-arch-stub.c |   26 +++++++++++++++++++++++++
>>>> target-mips/kvm-arch-stub.c       |   26 +++++++++++++++++++++++++
>>>> target-ppc/kvm-arch-stub.c        |   26 +++++++++++++++++++++++++
>>>> target-s390x/kvm-arch-stub.c      |   38 
>>>> +++++++++++++++++++++++++++++++++++++
>>>> target-sh4/kvm-arch-stub.c        |   26 +++++++++++++++++++++++++
>>>> target-sparc/kvm-arch-stub.c      |   26 +++++++++++++++++++++++++
>>>> target-unicore32/kvm-arch-stub.c  |   26 +++++++++++++++++++++++++
>>>> 14 files changed, 351 insertions(+), 1 deletions(-)
>>>> create mode 100644 target-alpha/kvm-arch-stub.c
>>>> create mode 100644 target-arm/kvm-arch-stub.c
>>>> create mode 100644 target-cris/kvm-arch-stub.c
>>>> create mode 100644 target-i386/kvm-arch-stub.c
>>>> create mode 100644 target-lm32/kvm-arch-stub.c
>>>> create mode 100644 target-m68k/kvm-arch-stub.c
>>>> create mode 100644 target-microblaze/kvm-arch-stub.c
>>>> create mode 100644 target-mips/kvm-arch-stub.c
>>>> create mode 100644 target-ppc/kvm-arch-stub.c
>>>> create mode 100644 target-s390x/kvm-arch-stub.c
>>>> create mode 100644 target-sh4/kvm-arch-stub.c
>>>> create mode 100644 target-sparc/kvm-arch-stub.c
>>>> create mode 100644 target-unicore32/kvm-arch-stub.c
>>> 
>>> Do we really want to create so much files on architectures we will never
>>> see KVM support? Actually I know very few things about KVM, so it would
>>> be better to have this patch reviewed by someone else. Avi or Anthony
>>> maybe?
>> 
>> Well, the main idea is to be able to have a unified place to put stub 
>> functions into. And as it stands with most generalizations, we either make 
>> it generic or not :).
>> Maybe there's some Makefile magic to only compile the stub if the file 
>> exists? I certainly don't know of any.
> 
> This approach looks wrong.
> 
> The point of kvm stubs is to allow generic components to be built
> independently of kvm enabled/disabled. But target-specific callbacks
> can't be part of generic components anyway. So there is no need for a
> stub, those bits will be built per-target anyway.
> 
> The examples you provided with this patch underline it:
> s390-virtio-bus.c should be built for s390 but nothing else.

And it is, yes. The point is to not require #ifdefs in device emulation code :).


Alex