Re: [libvirt] [PATCH 10/10] network: internal API functions to manage assignment of physdev to guest
On 07/08/2011 04:23 PM, Eric Blake wrote:
On 07/05/2011 10:18 PM, Laine Stump wrote:
> I realized that PATCH 10/10 would cause the build to fail if someone
> did a build --with-qemu but --without-network. I'm squashing the
> following into the original patch to remedy that.
>
> I'm not really a fan of putting #if all over the place, but this is
> similar to what's done with WITH_MACVTAP, so at least there's
> precedence. (This is necessary because this new "backend API" to the
> network driver isn't called via a pointer table filled in at runtime,
> as is done with the public API).
Would it be any easier to instead guarantee that even when #if
WITH_NETWORK is false, those same symbols are available as no-ops to
allow compilation to proceed?
That would mean either defining the functions inside qemu, or creating a
dummy network module replacement to be built when WITH_NETWORK is false.
I like both of those options even less.
> +#if WITH_NETWORK
> /* If appropriate, grab a physical device from the configured
> * network's pool of devices, or resolve bridge device name
> * to the one defined in the network definition.
> */
> if (networkAllocateActualDevice(net)< 0)
> goto error;
> -
> +#endif
That is, make networkAllocateActualDevice() be a no-op that returns 0 if
there is no network support compiled in, and therefore nothing to allocate.
But where would that NOP function live? The natural place for a function
called "networkSomething" is in a network driver, but there isn't one.
> +++ b/tests/Makefile.am
> @@ -319,8 +319,11 @@ endif
>
> if WITH_QEMU
>
> -qemu_LDADDS = ../src/libvirt_driver_qemu.la \
> - ../src/libvirt_driver_network.la
> +qemu_LDADDS = ../src/libvirt_driver_qemu.la
> +
> +if WITH_NETWORK
> +qemu_LDADDS += ../src/libvirt_driver_network.la
> +endif
Then again, if you are compiling --without-network, you don't want to
link against a library that won't be built. That would imply that any
no-op stubs would have to be provided by static inline functions in the
header in the no-network case.
Ah, you're doing this mail "On the Road" style (stream of consciousness
with no going back to edit), so I'll respond that way too :-)
Actually, I like this idea - in bridge_driver.h, I can put the function
declrations inside #if WITH_NETWORK, and have a #else clause that
contains inlines that return success but do nothing (exactly what is
needed). That way the code in qemu won't need #if.
I'll do it that way in the next version.