Re: [PATCH v7 5/6] tools: Allow building xen-hptool without CONFIG_MIGRATE

[Jan Beulich <jbeulich@xxxxxxxx>]

On 15.04.2026 16:51, Mykyta Poturai wrote:
> On 3/30/26 15:32, Jan Beulich wrote:
>> On 30.03.2026 13:59, Mykyta Poturai wrote:
>>> With CPU hotplug sysctls implemented on Arm it becomes useful to have a
>>> tool for calling them.
>>>
>>> According to the commit history it seems that putting hptool under
>>> config MIGRATE was a measure to fix IA64 build. As IA64 is no longer
>>> supported it can now be brought back. So build it unconditionally.
>>>
>>> Signed-off-by: Mykyta Poturai <mykyta_poturai@xxxxxxxx>
>>> ---
>>> v6->v7:
>>> * no changes
>>>
>>> v5->v6:
>>> * don't change order in Makefile
>>>
>>> v4->v5:
>>> * make hptool always build
>>>
>>> v3->v4:
>>> * no changes
>>>
>>> v2->v3:
>>> * no changes
>>>
>>> v1->v2:
>>> * switch to configure from legacy config
>>> ---
>>>   tools/libs/guest/Makefile.common | 2 +-
>>>   tools/misc/Makefile              | 2 +-
>>>   2 files changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/tools/libs/guest/Makefile.common 
>>> b/tools/libs/guest/Makefile.common
>>> index b928a4a246..03dfcee7fa 100644
>>> --- a/tools/libs/guest/Makefile.common
>>> +++ b/tools/libs/guest/Makefile.common
>>> @@ -7,6 +7,7 @@ OBJS-y += xg_private.o
>>>   OBJS-y += xg_domain.o
>>>   OBJS-y += xg_suspend.o
>>>   OBJS-y += xg_resume.o
>>> +OBJS-y += xg_offline_page.o
>>>   ifeq ($(CONFIG_MIGRATE),y)
>>>   OBJS-y += xg_sr_common.o
>>>   OBJS-$(CONFIG_X86) += xg_sr_common_x86.o
>>> @@ -17,7 +18,6 @@ OBJS-$(CONFIG_X86) += xg_sr_save_x86_pv.o
>>>   OBJS-$(CONFIG_X86) += xg_sr_save_x86_hvm.o
>>>   OBJS-y += xg_sr_restore.o
>>>   OBJS-y += xg_sr_save.o
>>> -OBJS-y += xg_offline_page.o
>>>   else
>>>   OBJS-y += xg_nomigrate.o
>>>   endif
>>
>> This looks wrong to me. There are x86-specifics in that file, which shouldn't
>> be built on Arm. And the name of the file also doesn't indicate any relation
>> to CPU management.
> 
> xen-hptool requires xg_offline_page as it has both CPU and memory 
> hotplug commands. Without building xg_offline_page it fails with
> 
> xen-hptool: symbol lookup error: xen-hptool: undefined symbol: 
> xc_mark_page_offline, version libxenguest_4.22.0
> 
> when trying to do memory ops.
> 
> Is it an acceptable behavior?

I don't think so, no. The tool wouldn't, aiui, load at all then if built with
"bindnow" enabled.

> If so I guess we can build xg_offline page only on x86.

We still need to, imo. But the tool still needs to be usable no matter how
specifically it is built. It should avoid referencing xg_offline_page.c
functions when built for non-x86.

Jan