[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH] evtchn: make support for different ABIs tunable

On 14.08.19 15:02, Andrew Cooper wrote:
On 14/08/2019 13:51, George Dunlap wrote:
On 8/7/19 5:03 PM, Jan Beulich wrote:
Whatever we do in Xen, it'll only allow to work around that issue.
An actual fix belongs in the kernel(s). For this reason I suppose
what we're talking about here is a feature (from Xen's pov), not a
bug fix. And it being a feature, it should preferably be coded in
a way that's usable also going forward.
FWIW, I agree with what I understand Jan to be saying:

1. It would be good to be able to disable FIFO event channels, but

2. Disabling them in Xen isn't really the right way to fix Amazon's
issue. Rather, probably the soft reboot should reset the event channel

Depends what you mean about "fix the issue".

Amazon have real customer VMs in this situation which will break on a
Xen old => new upgrade.  Modifying Xen is the only rational option.

They are also doing this in an upstream compatible manner (which is
great).  One way or another, Xen needs to gain this ability to work
around broken-linux which is already in the field.

As for the ideal way to fix this, this bug has existed in Linux longer
than soft-reset has been a thing, and frankly, its still a gruesome
hack.  We need some interfaces which don't suck so terribly.


Thanks, Andrew. I second those points.

I have just sent v3 of this patch, mostly addressing comments from Jan. Have a look, and let me know if there are further tweaks you would rather see. Thanks.


Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.