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


From: Anthony Liguori
Subject: Re: [Qemu-devel] hw/Makefile.objs question
Date: Thu, 21 Jun 2012 08:23:20 -0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120329 Thunderbird/11.0.1

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.








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