Re: [PATCH 1/9] hw/mem: Add tag support to generic host memory backends

[Markus Armbruster <armbru@redhat.com>]

Alireza Sanaee <alireza.sanaee@huawei.com> writes:

> On Thu, 26 Mar 2026 11:42:17 +0100
> Markus Armbruster <armbru@redhat.com> wrote:
>
> Hi Markus,
>
>> Alireza Sanaee <alireza.sanaee@huawei.com> writes:
>> 
>> > Add a string tag property to HostMemoryBackend so that backends can be
>> > identified by a user-assigned name at runtime. Expose the property through
>> > QOM and add a host_memory_backend_find_by_tag() helper that walks the
>> > object tree to locate a backend by its tag.  
>> 
>> Why can't you use the QOM ID?
>> 
>> $ qemu-system-x86_64 -S -display none -monitor stdio -object memory-backend-ram,id=fred,size=1M
>> QEMU 10.2.90 monitor - type 'help' for more information
>> (qemu) info qom-tree /objects/fred
>> /fred (memory-backend-ram)
>>   /fred[0] (memory-region)
>> 
>>  
>
> Fair question. The ID would have been a solution if it had accepted GUIDs. CXL spec 
> requires GUIDs for extents as identification, hence new tag property.

Your commit message should state that this needs to be a GUID and why.

> alireza@blue-ocean:~/Downloads$ qemu-system-x86_64 -s -display none -monitor std
> io -object memory-backend-ram,id=02bb2436-e87d-4aa1-b2be-aaffdd76bb79,size=1M
> qemu-system-x86_64: -object memory-backend-ram,id=02bb2436-e87d-4aa1-b2be-aaffdd
> 76bb79,size=1M: Parameter 'id' expects an identifier
> Identifiers consist of letters, digits, '-', '.', '_', starting with a letter.
>
> Thanks,
> Ali