On 27.11.19 01:01, Julien Grall wrote:
Hi,
On 26/11/2019 23:17, Stefano Stabellini wrote:
On Tue, 26 Nov 2019, Julien Grall wrote:
Hi,
On 26/11/2019 20:43, Stefano Stabellini wrote:
+ Juergen
I missed that you weren't in CC to the original patch, sorry.
I think this patch should go in, as otherwise Linux 5.4 could run into
problems. It is also a pretty straightforward 4 lines patch.
5.5 (or 5.6) is not going to run on Xen for other reasons (still in the
vGIC)... So I would not view this as critical.
5.5 is not out yet, in fact, the dev window has just opened. Isn't your
statement a bit premature?
The GICv4.1 work [1] is going to prevent Linux booting on all current
versions of Xen. While I can't confirm this is going to be merged in
5.5, I can tell you this will break.
In any case, even if potential future Linux releases could have other
additional issues, I don't think it should change our current view on
this specific issue which affects 5.4, just released.
The patch is definitely not as straightforward as you may think. Please
refer to the discussion we had on the first version. I voiced concern
about this approach and gave point what could go wrong with happen.
This patch may be better than the current state (i.e crashing), but this
wasn't tested enough to confirm this is the correct things to do and no
other bug will appear (I don't believe reading I*ACTIVER was ever tested
before).
It is an annoying bug, but this is only affecting 5.4 which has just
been released. It feels to me this is a fairly risky choice to merge it
qutie late in the release without a good graps of the problem (see above).
So I would definitly, prefer if this patch is getting through backport
once we get more testing.
We can still document the bug in the release note and point people to
the patch.
Anyway, this is Juergen choice here. But at least now he has the full
picture...
Cheers,
[1] https://lwn.net/Articles/800494/
Thanks, Julien, for sharing your opinion.
With that statement I'd like to defer this patch to 4.14.
Juergen
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