Re: [PATCH v4 2/2] xen/arm: Enlarge identity map space to 10TB

[Julien Grall <julien@xxxxxxx>]

Hi Stefano,

On 17/10/2023 20:58, Stefano Stabellini wrote:
> > And therefore a Fixes tag is sensible. This doesn't mean I would want to
> > backport it right now (note that only 4.18 is affected). But this could change
> > in the future if we get another report (post-4.18) on a platform where there
> > are no other workaround.
> >
> > Stefano any opinions?
> The Fixes tag carries useful information but the problem is that it is
> typically used for identifying backports and this is not a backport (at
> least today we would not consider it a backport).
Below the definition of Fixes tag (from  process/sending-patches.pandoc):

If your patch fixes a bug in a specific commit, e.g. you found an issue 
using ``git bisect``, please use the `Fixes:` tag with the first 12 
characters of the commit id, and the one line summary.
This doesn't say anything about backport. In fact, we introduced a 
separate tag for that (see Backport).
> So I would provide the same information but without using the Fixes tag.
> For instance: "This commit fixes an issue that was introduced by XXX
> because of YYY and only affects the AVA platform with not up-to-date
> firmware".
The part after 'and' is misleading. So far we had a report only on AVA 
platform but this doesn't mean it couldn't happen on other HW. The same 
is true with the new limit.
So this wants to be:

"and so far we only had a report for the AVA platform when using UEFI 
older than vX."
> That way, we avoid the risk of someone taking all the applicable commits
> with a Fixes tag and backporting them without thinking twice about it.
> But we still have the information in the git log.
I don't really see the problem for someone to mistakenly backport this 
patch. In fact, this could potentially save them a lot of debugging if 
it happens that Xen is loaded above 2TB.
Anyway, both Bertrand and you seems to be against the Fixes tag here. So 
I can compromise with the "This commit fixes...". However, can Bertrand 
or you update process/send-patches.pandoc so it is clear for a 
contributor when they should add Fixes tag (which BTW I still disagree 
with but if the majority agrees, then I will not nack)?
Regarding this patch itself, Stefano can you queue to your branch for-4.19?

Cheers,

--
Julien Grall