Re: [Qemu-devel] [PATCH 33/52] build: switch to Kconfig

[Philippe Mathieu-Daudé]

On 1/31/19 11:15 PM, Paolo Bonzini wrote:
> On 31/01/19 22:48, Philippe Mathieu-Daudé wrote:
>> There is something I don't understand here: Does CONFIG_XEN in
>> Kconfig.host take precedence over the target configs? I'm looking at
>> these configs:
>>
>>  if supported_xen_target $target; then
>>      echo "CONFIG_XEN=n" >> $config_target_mak
>>      if test "$xen_pci_passthrough" = yes; then
>>          echo "CONFIG_XEN_PCI_PASSTHROUGH=y" >> "$config_target_mak"
>>      fi
>>  fi
> 
> You're right, Kconfig.host should contain CONFIG_XEN_BACKEND and not
> CONFIG_XEN.

Now when I disable Xen, exec.o isn't rebuilt, so I get link errors:

/usr/bin/ld: exec.o: in function `reclaim_ramblock':
qemu/exec.c:2392: undefined reference to `xen_invalidate_map_cache_entry'
/usr/bin/ld: exec.o: in function `qemu_ram_ptr_length':
qemu/exec.c:2531: undefined reference to `xen_map_cache'
/usr/bin/ld: exec.o: in function `qemu_map_ram_ptr':
qemu/exec.c:2498: undefined reference to `xen_map_cache'
/usr/bin/ld: exec.o: in function `qemu_ram_block_from_host':
qemu/exec.c:2573: undefined reference to `xen_ram_addr_from_mapcache'
/usr/bin/ld: exec.o: in function `address_space_unmap':
qemu/exec.c:3699: undefined reference to `xen_invalidate_map_cache_entry'
/usr/bin/ld: exec.o: in function `address_space_cache_destroy':
qemu/exec.c:3791: undefined reference to `xen_invalidate_map_cache_entry'
/usr/bin/ld: exec.o: in function `qemu_ram_ptr_length':
qemu/exec.c:2528: undefined reference to `xen_map_cache'
/usr/bin/ld: exec.o: in function `qemu_map_ram_ptr':
qemu/exec.c:2495: undefined reference to `xen_map_cache'
collect2: error: ld returned 1 exit status
make[1]: *** [Makefile:204: qemu-system-i386] Error 1

Moving those function stubs into a real xen-stub.c file would be simpler
from the buildsys PoV IMHO, but I also remember we prefer to avoid
stubs, so not sure what's better here, neither what's wrong with make rules.