Re: [Qemu-devel] [PATCH] quorum: Only compile when supported

["Daniel P. Berrange" <berrange@redhat.com>]

On Tue, Jun 28, 2016 at 09:47:47AM +0800, Fam Zheng wrote:
> This was the only exceptional module init function that does something
> else than a simple list of bdrv_register() calls, in all the block
> drivers.
> 
> The qcrypto_hash_supports is actually a static check, determined at
> compile time.  Follow the block-job-$(CONFIG_FOO) convention for
> consistency.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>

The point of using qcrypto_hash_supports() is that it isolates the
block code Makefile rules from the details of the current specific
impl of the hash APIs in QEMU. As a prime example of why this is
important, try rebasing to GIT master, and you'll find we no longer
use gnutls for the hash APIs. We choose between libgcrypt, nettle
or a empty stub for hash impls now. I think it is a backwards step
to add back these makefile conditionals

> ---
>  block/Makefile.objs | 2 +-
>  block/quorum.c      | 4 ----
>  2 files changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/block/Makefile.objs b/block/Makefile.objs
> index 44a5416..c87d605 100644
> --- a/block/Makefile.objs
> +++ b/block/Makefile.objs
> @@ -3,7 +3,7 @@ block-obj-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o qcow2-c
>  block-obj-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o qed-cluster.o
>  block-obj-y += qed-check.o
>  block-obj-$(CONFIG_VHDX) += vhdx.o vhdx-endian.o vhdx-log.o
> -block-obj-y += quorum.o
> +block-obj-$(CONFIG_GNUTLS_HASH) += quorum.o
>  block-obj-y += parallels.o blkdebug.o blkverify.o blkreplay.o
>  block-obj-y += block-backend.o snapshot.o qapi.o
>  block-obj-$(CONFIG_WIN32) += raw-win32.o win32-aio.o
> diff --git a/block/quorum.c b/block/quorum.c
> index 331b726..18fbed8 100644
> --- a/block/quorum.c
> +++ b/block/quorum.c
> @@ -1113,10 +1113,6 @@ static BlockDriver bdrv_quorum = {
>  
>  static void bdrv_quorum_init(void)
>  {
> -    if (!qcrypto_hash_supports(QCRYPTO_HASH_ALG_SHA256)) {
> -        /* SHA256 hash support is required for quorum device */
> -        return;
> -    }
>      bdrv_register(&bdrv_quorum);
>  }
>  
> -- 
> 2.9.0
> 
> 

Regards,
Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|