Re: [Qemu-devel] [PATCH v2 1/9] configure: change CONFIG_XEN_BACKEND to be a target property

[Paolo Bonzini <pbonzini@redhat.com>]

On 14/03/2017 21:23, Stefano Stabellini wrote:
> On Tue, 14 Mar 2017, Stefano Stabellini wrote:
>>> Then you add to Makefile:
>>>
>>>  CONFIG_SOFTMMU := $(if $(filter %-softmmu,$(TARGET_DIRS)),y)
>>>  CONFIG_USER_ONLY := $(if $(filter %-user,$(TARGET_DIRS)),y)
>>> +CONFIG_XEN := $(CONFIG_XEN_BACKEND)
>>>  CONFIG_ALL=y
>>>  -include config-all-devices.mak
>>>  -include config-all-disas.mak
>>>
>>> The Makefile change ensures that they are built before descending in the
>>> target-specific directories.
>>
>> But I don't understand this. Please correct me if I am wrong, but this
>> change looks like it would end up setting CONFIG_XEN every time that
>> CONFIG_XEN_BACKEND is set. Without the configure change at the top, it
>> would end up setting CONFIG_XEN whenever the host supports Xen, even for
>> non-x86 and non-ARM targets. What am I missing?

This CONFIG_XEN assignment applies to the toplevel only, i.e. to files
that are built once.  Targets will still take CONFIG_XEN from
config-target.mak, and it will not be set for non-x86/non-ARM targets.
This CONFIG_XEN assignment applies to files that are compiled once.

The issue you reported here:

>   LINK    aarch64-softmmu/qemu-system-aarch64
> ../hw/9pfs/xen-9p-backend.o: In function `xen_9pfs_alloc':
> /local/qemu/hw/9pfs/xen-9p-backend.c:387: undefined reference to `xenstore_write_be_str'
> /local/qemu/hw/9pfs/xen-9p-backend.c:388: undefined reference to `xenstore_write_be_int'

is because you need this in patch 9:

-common-obj-$(CONFIG_XEN_BACKEND) += xen-9p-backend.o
+common-obj-$(CONFIG_XEN) += xen-9p-backend.o


> ../hw/9pfs/xen-9p-backend.o: In function `xen_9pfs_connect':
> /local/qemu/hw/9pfs/xen-9p-backend.c:292: undefined reference to `xenstore_read_fe_int'
> /local/qemu/hw/9pfs/xen-9p-backend.c:313: undefined reference to `xenstore_read_fe_int'
> /local/qemu/hw/9pfs/xen-9p-backend.c:357: undefined reference to `xen_pv_printf'
> /local/qemu/hw/9pfs/xen-9p-backend.c:307: undefined reference to `xenstore_read_fe_int'
> /local/qemu/hw/9pfs/xen-9p-backend.c:362: undefined reference to `xenstore_read_be_str'
> /local/qemu/hw/9pfs/xen-9p-backend.c:363: undefined reference to `xenstore_read_be_str'
> /local/qemu/hw/9pfs/xen-9p-backend.c:366: undefined reference to `xenstore_read_fe_str'
> /local/qemu/hw/9pfs/xen-9p-backend.c:353: undefined reference to `xen_pv_printf'
> ../hw/9pfs/xen-9p-backend.o: In function `xen_9pfs_alloc':
> /local/qemu/hw/9pfs/xen-9p-backend.c:389: undefined reference to `xenstore_write_be_int'
> collect2: error: ld returned 1 exit status
> make[1]: *** [qemu-system-arm] Error 1
> make: *** [subdir-arm-softmmu] Error 2
> ../hw/9pfs/xen-9p-backend.o: In function `xen_9pfs_alloc':
> /local/qemu/hw/9pfs/xen-9p-backend.c:387: undefined reference to `xenstore_write_be_str'
> /local/qemu/hw/9pfs/xen-9p-backend.c:388: undefined reference to `xenstore_write_be_int'
> ../hw/9pfs/xen-9p-backend.o: In function `xen_9pfs_connect':
> /local/qemu/hw/9pfs/xen-9p-backend.c:292: undefined reference to `xenstore_read_fe_int'
> /local/qemu/hw/9pfs/xen-9p-backend.c:313: undefined reference to `xenstore_read_fe_int'
> /local/qemu/hw/9pfs/xen-9p-backend.c:357: undefined reference to `xen_pv_printf'
> /local/qemu/hw/9pfs/xen-9p-backend.c:307: undefined reference to `xenstore_read_fe_int'
> /local/qemu/hw/9pfs/xen-9p-backend.c:362: undefined reference to `xenstore_read_be_str'
> /local/qemu/hw/9pfs/xen-9p-backend.c:363: undefined reference to `xenstore_read_be_str'
> /local/qemu/hw/9pfs/xen-9p-backend.c:366: undefined reference to `xenstore_read_fe_str'
> /local/qemu/hw/9pfs/xen-9p-backend.c:353: undefined reference to `xen_pv_printf'
> ../hw/9pfs/xen-9p-backend.o: In function `xen_9pfs_alloc':
> /local/qemu/hw/9pfs/xen-9p-backend.c:389: undefined reference to `xenstore_write_be_int'
> collect2: error: ld returned 1 exit status
> make[1]: *** [qemu-system-aarch64] Error 1
> make: *** [subdir-aarch64-softmmu] Error 2
> 
> 
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