spice backend fails to build on i386 with -Werror

[Steve Langasek]

Because qemu-linaro 2012.01 is now based on a development release of qemu (1.0.50 instead of 1.0), the configure script turns on -Werror for building by default. This causes a problem for the recently-enabled spice support, because of some mismatched integer sizes on 32-bit systems.

  CC i386-softmmu/qxl.o
/home/vorlon/devel/linaro/qemu-linaro-fakeout/build-area/qemu-linaro-1.0.50-2012.01/hw/qxl.c: In function 'interface_release_resource':
/home/vorlon/devel/linaro/qemu-linaro-fakeout/build-area/qemu-linaro-1.0.50-2012.01/hw/qxl.c:631:46: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
/home/vorlon/devel/linaro/qemu-linaro-fakeout/build-area/qemu-linaro-1.0.50-2012.01/hw/qxl.c: In function 'interface_async_complete':
/home/vorlon/devel/linaro/qemu-linaro-fakeout/build-area/qemu-linaro-1.0.50-2012.01/hw/qxl.c:754:5: error: format '%ld' expects argument of type 'long int', but argument 4 has type 'uint64_t' [-Werror=format]
/home/vorlon/devel/linaro/qemu-linaro-fakeout/build-area/qemu-linaro-1.0.50-2012.01/hw/qxl.c: In function 'qxl_phys2virt':
/home/vorlon/devel/linaro/qemu-linaro-fakeout/build-area/qemu-linaro-1.0.50-2012.01/hw/qxl.c:1021:16: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
cc1: all warnings being treated as errors

make[3]: *** [qxl.o] Error 1

This is a strange sort of bug; usually software gets size mismatches on 64-bit systems, not on 32-bit systems. In this case, spice upstream has defined a struct to use a 64-bit integer, so casting a 32-bit pointer in and out of it produces the above errors.

It may be an error that upstream is specifying uint64_t here instead of, say, intptr_t or unsigned long. So feel free to redirect this to spice upstream - since the spice-protocol package only produces headers and not a library, there are no ABI consequences to changing the type there AFAICS.

In the meantime I've worked around this failure in the Ubuntu package by passing --disable-werror for the spice build.

[Peter Maydell (pmaydell)]

Last time I asked, Spice simply doesn't work/isn't supported on 32 bit hosts. Better to disable spice on the 32 bit builds I guess?

[Rusty Russell (rusty-rustcorp)]

Indeed, FAQ on wiki makes it clear. I don't know why Ubuntu even allows packages libspice-server-dev for i386, but I hit this too.

[Steve Langasek (vorlon)]

Ah; libspice-*-dev are architecture: all packages since they don't require rebuilding for different archs (they're just headers being shipped), so they're available on i386 even if not meant to be used. We can fix the package to not build-depend on them.

[Peter Maydell (pmaydell)]

Rusty: there's a typo there ("probel") but can you submit a version of that patch for upstream qemu to qemu-devel, please?

[Launchpad Janitor (janitor)]

This bug was fixed in the package qemu-linaro - 1.0.50-2012.01-0ubuntu3

---------------
qemu-linaro (1.0.50-2012.01-0ubuntu3) precise; urgency=low

  * Don't build the qemu-kvm-spice package on i386, spice is 64-bit-only.
    LP: #928432.
  * This means we don't have to disable -Werror on the spice build anymore.
 -- Steve Langasek <email address hidden> Tue, 07 Feb 2012 23:34:36 +0000

[Peter Maydell (pmaydell)]

Upstream says that apparently Spice does work on 32 bit hosts now (the FAQ is out of date). I've put the necessary compilation warning fixes into qemu-linaro pending them being committed upstream.

Steve: this means you'll want to unwind the 'don't build qemu-kvm-spice on i386' change in the packaging.

[Steve Langasek (vorlon)]

reopening the Ubuntu task then, so we can revert this change in the next upload.

[Ubuntu Foundations Team Bug Bot (crichton)]

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[Steve Langasek (vorlon)]

Building qemu-linaro 2012.03 on i386 still fails with the following errors:

/home/vorlon/devel/linaro/qemu-linaro/build-area/qemu-linaro-1.0.50-2012.03/hw/qxl.c: In function 'qxl_spice_update_area':
/home/vorlon/devel/linaro/qemu-linaro/build-area/qemu-linaro-1.0.50-2012.03/hw/qxl.c:152:57: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
/home/vorlon/devel/linaro/qemu-linaro/build-area/qemu-linaro-1.0.50-2012.03/hw/qxl.c: In function 'qxl_spice_destroy_surface_wait':
/home/vorlon/devel/linaro/qemu-linaro/build-area/qemu-linaro-1.0.50-2012.03/hw/qxl.c:174:60: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
/home/vorlon/devel/linaro/qemu-linaro/build-area/qemu-linaro-1.0.50-2012.03/hw/qxl.c: In function 'qxl_spice_flush_surfaces_async':
/home/vorlon/devel/linaro/qemu-linaro/build-area/qemu-linaro-1.0.50-2012.03/hw/qxl.c:184:9: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
/home/vorlon/devel/linaro/qemu-linaro/build-area/qemu-linaro-1.0.50-2012.03/hw/qxl.c: In function 'qxl_spice_destroy_surfaces':
/home/vorlon/devel/linaro/qemu-linaro/build-area/qemu-linaro-1.0.50-2012.03/hw/qxl.c:216:17: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
/home/vorlon/devel/linaro/qemu-linaro/build-area/qemu-linaro-1.0.50-2012.03/hw/qxl.c: In function 'interface_async_complete_io':
/home/vorlon/devel/linaro/qemu-linaro/build-area/qemu-linaro-1.0.50-2012.03/hw/qxl.c:747:17: error: format '%ld' expects argument of type 'long int', but argument 5 has type 'uint64_t' [-Werror=format]
/home/vorlon/devel/linaro/qemu-linaro/build-area/qemu-linaro-1.0.50-2012.03/hw/qxl.c: In function 'interface_async_complete':
/home/vorlon/devel/linaro/qemu-linaro/build-area/qemu-linaro-1.0.50-2012.03/hw/qxl.c:815:25: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]

[Peter Maydell (pmaydell)]

Oops. My test of this was on a 32 bit oneiric system, where configure now disables spice completely. Retested and reproduced on a precise-i386 chroot, and sent a patch upstream:
http://patchwork.ozlabs.org/patch/147207/

[Peter Maydell (pmaydell)]

This time for sure!

[Jeremy Bícha (jbicha)]

I believe this has been fixed for Ubuntu 13.04 "Raring":

https://launchpad.net/ubuntu/+source/qemu-linaro/1.2.0-2012.09-0ubuntu2