Re: [Qemu-devel] hw/Makefile.objs question

[Anthony Liguori <anthony@codemonkey.ws>]

On 06/21/2012 08:10 AM, Alexey Kardashevskiy wrote:
> On 21/06/12 22:19, Andreas Färber wrote:
>> Am 21.06.2012 13:21, schrieb Alexey Kardashevskiy:
>>> On 21/06/12 20:36, Andreas Färber wrote:
>>>> Am 21.06.2012 05:22, schrieb Alexey Kardashevskiy:
>>>>> I am trying to compile the very last qemu with vfio_pci enabled. VFIO_PCI is added as below:
>>>>>
>>>>> ./configure:
>>>>>
>>>>>   case "$target_arch2" in
>>>>>    i386|x86_64|ppc64)
>>>>>       if test "$vfio_pci" = "yes" -a "$target_softmmu" = "yes" ; then
>>>>>         echo "CONFIG_VFIO_PCI=y">>  $config_target_mak
>>>>>       fi
>>>>>   esac
>>>>>
>>>>>
>>>>> ./Makefile.target:
>>>>>
>>>>>   # VFIO PCI device assignment
>>>>> obj-$(CONFIG_VFIO_PCI) += vfio_pci.o
>>>>>
>>>>>
>>>>> And it worked before. However it does not anymore as it seems that everything in hw/ (and vfio_pci.c
>>>>> as well as is in hw/ and it is a device) can be only compiled via hw/Makefile.objs and
>>>>> hw/ppc/Makefile.objs (my platform is POWER), it is ignored if to keep it as is.
>>>>>
>>>>> So I have to move "obj-$(CONFIG_VFIO_PCI) += vfio_pci.o" to hw/Makefile.objs (and change obj- to
>>>>> hw-obj-) but the hw/Makefile.objs does not include (directly or indirectly) generated
>>>>> ppc64-softmmu/config-target.mak with CONFIG_VFIO_PCI=y.
>>>>>
>>>>> What is the correct solution?
>>>>
>>>> If the file compiles the same for all three, put CONFIG_VFIO_PCI=y into
>>>> default-configs/{i386,x86_64,ppc64}-softmmu.mak and do
>>>> hw-obj-$(CONFIG_VFIO_PCI) += in hw/Makefile.objs.
>>>
>>>
>>> It only compiles with ./configure --enable-vfio-pci which may or may not set CONFIG_VFIO_PCI to "y".
>>> Your proposal makes it always "y" (for selected platforms).
>>
>> Apply some creativity, there's surely examples around. The question is
>> whether the contents of vfio_pci.o changes or not.
>
> Applied already and gave up, this is why I am writing here :)
> What would be a good example of a device which is enabled by configure script?

We don't have a great way to do this.  CONFIG_VIRTFS is the best example.

You need three things:

1) a CONFIG_ variable set by configure (whether the user wants VFIO)

2) a CONFIG_ variable set by the target default-config/ whether the board 
supports VFIO.  This could just be CONFIG_PCI btw.

3) a variable that you create in Makefile.objs that is only set if (1) && (2) 
are both set to y

You can then use the variable from (3) to do obj-$(CONFIG_...) in the 
appropriate Makefiles.obj.

Regards,

Anthony Liguori

>
>> If not, then you only
>> need to build it once in libhwX/, depending on $config_target_mak, and
>> link to the appropriate targets. If it accesses CPU internals then it
>> must be built per target.
>
> $config_target_mak points to ppc64-softmmu/config-target.mak, not in the root folder.
> When executed in libhw64, it is not visible to makefile.
>
>
>>>> Otherwise, add to hw/{i386,ppc}/Makefile.objs - or with Anthony's
>>>> proposal from yesterday hw/Makefile.objs becomes possible, too.
>>>
>>> Again, it will be unconditional "y".
>>
>> No, in this case the condition would be set from configure as before, it
>> only moves from Makefile.target to the appropriate Makefile.objs.
>> Note that to limit it to ppc64 (as opposed to ppc) some additional ifeq
>> check would be needed, as before.
>
>
>
>