Re: [PATCH v3 05/44] gdb, gdbserver, gdbsupport: add 'device' tag to XML target description

[Simon Marchi <simark@simark.ca>]

On 12/9/25 4:27 PM, Simon Marchi wrote:
> On 8/1/25 5:37 AM, Tankut Baris Aktemur wrote:
>> From: Nils-Christian Kempke <nils-christian.kempke@intel.com>
>>
>> Add <device> tag to the XML target description.  The tag is a list of
>> device attributes.  The extension enables passing device information
>> within the target description XML sent from gdbserver to gdb.
> 
> The dtd change allows a single <device> in the target description.  When
> (and if) you do multi-device debugging, you connect one inferior per
> device?
> 
> From the ROCm perspective: if we ever want to support remote debugging
> (no concrete plans, but we want to keep the door open to it in the
> design) and we end up using this attribute, I suppose we'll want to be
> able to use multiple <device> tags, since we do everything in a single
> inferior.  If so, it would be easier to support that possibility from
> the start.

I talked about that with my team, and what I proposed doesn't make
sense.  The entire target description describes just one arch, it
wouldn't make sense to have multiple devices of possibly different
arches in it.

In ROCgdb, we have an "info agents" command, which lists the agents
(devices) available to the current inferior (process).  You can, for
instance, stop at main(), and then type "info agents" to get the list.
Therefore, I presume that we would instead need a new kind of query,
"get me the list of devices", and that query could re-use the XML device
format proposed in this patch.

Another question I have is whether the low-level details specific to one
device should really belong there in the target description.  In other
words, imagine that you debug with two identical devices simultaneously,
should the target descriptions for both devices be identical?  I tend to
think that they should.  Perhaps things like pci_slot shouldn't be in
the target description, but in a separate "device" concept outside
target descriptions.  Things like vendor_id and target_id allow
inferring details about the architecture, so I understand why it would
be in there.

Simon