Both the protocol part (and the now removed client part) seem to have some x86/x86_64 specific inline assembly in it making the code unportable. After removing the client issue spice compiles, but e.g. qemu with spice enable still fails to compile due to protocol.

For reference the client patch I used is to just remove the debug breakpoint:
http://git.alpinelinux.org/cgit/aports/tree/main/spice/fix-non-x86-build.patch

The inline assembly protocol part is in spice-common/spice-protocol/spice/barrier.h.

Qemu build on ARM fails with:

  CC    hw/display/qxl.o
  CC    hw/display/qxl-logger.o
  CC    hw/display/qxl-render.o
{standard input}: Assembler messages:
{standard input}:1593: Error: bad instruction `lock'
{standard input}:1593: Error: bad instruction `addl $0,0(%rsp)'
{standard input}:1740: Error: bad instruction `lock'
{standard input}:1740: Error: bad instruction `addl $0,0(%rsp)'
{standard input}:3882: Error: bad instruction `lock'
{standard input}:3882: Error: bad instruction `addl $0,0(%rsp)'
  CC    hw/dma/puv3_dma.o
{standard input}:6349: Error: bad instruction `lock'
{standard input}:6349: Error: bad instruction `addl $0,0(%rsp)'
  CC    hw/dma/rc4030.o
{standard input}:9162: Error: bad instruction `lock'
{standard input}:9162: Error: bad instruction `addl $0,0(%rsp)'
{standard input}:10359: Error: bad instruction `lock'
{standard input}:10359: Error: bad instruction `addl $0,0(%rsp)'
{standard input}:10674: Error: bad instruction `lock'
{standard input}:10674: Error: bad instruction `addl $0,0(%rsp)'
/home/buildozer/aports/main/qemu/src/qemu-2.1.2/rules.mak:31: recipe for target 'hw/display/qxl.o' failed
make: *** [hw/display/qxl.o] Error 1
 
The bad instructions come from spice's barrier.h.