Re: [PATCH net-next] net/mlx4_core: Fix backward compatibility on VFs

On Fri, Mar 18, 2016 at 11:11:06PM -0400, David Miller wrote:

From: Eli Cohen <eli-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Date: Thu, 17 Mar 2016 18:49:42 +0200

quoted

Commit 85743f1eb345 ("net/mlx4_core: Set UAR page size to 4KB regardless
of system page size") introduced dependency where old VF drivers without
this fix fail to load if the PF driver runs with this commit.

To resolve this add a module parameter which disables that functionality
by default.  If both the PF and VFs are running with a driver with that
commit the administrator may set the module param to true.

The module parameter is called enable_4k_uar.

Can you consider passing this via comm-channel and save us all from new
module parameter?
Suggesting this from sys-admin perspective where (1) making this consist in
VF and **all** guests would me a nightmare and also (2) take into account
in public cloud that hypervisor sys-admin is not necessary the same person
as guest sys-admin.

quoted

Fixes: 85743f1eb345 ('net/mlx4_core: Set UAR page size to 4KB ...')
Signed-off-by: Eli Cohen <eli-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>

Applied.
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On Sun, Mar 20, 2016 at 9:07 AM, Yuval Shaia [off-list ref] wrote:

On Fri, Mar 18, 2016 at 11:11:06PM -0400, David Miller wrote:

quoted

From: Eli Cohen <redacted>
Date: Thu, 17 Mar 2016 18:49:42 +0200

quoted

quoted

Commit 85743f1eb345 ("net/mlx4_core: Set UAR page size to 4KB regardless
of system page size") introduced dependency where old VF drivers without
this fix fail to load if the PF driver runs with this commit.
To resolve this add a module parameter which disables that functionality
by default.  If both the PF and VFs are running with a driver with that
commit the administrator may set the module param to true.
The module parameter is called enable_4k_uar.

Can you consider passing this via comm-channel and save us all from new
module parameter?
Suggesting this from sys-admin perspective where (1) making this consist in
VF and **all** guests would me a nightmare and also (2) take into account
in public cloud that hypervisor sys-admin is not necessary the same person
as guest sys-admin.

AFAIK both modified (e.g containing the offending commit) and
non-modified VF drivers
need not be aware to the fix. It should be  a PF only param, where all types of
VF driver keeps working with their source of info being the comm-channel only.

Eli, Yishai, can you confirm this is the case?

Or.