On Tue, Aug 28, 2018 at 6:22 PM Arnd Bergmann [off-list ref] wrote:

On Tue, Aug 28, 2018 at 2:48 PM Sunil Kovvuri [off-list ref] wrote:

quoted

On Tue, Aug 28, 2018 at 5:33 PM Arnd Bergmann [off-list ref] wrote:

quoted

On Tue, Aug 28, 2018 at 12:57 PM [off-list ref] wrote:

quoted

From: Aleksey Makarov <redacted>

This patch adds mailbox support infrastructure APIs.
Each RVU device has a dedicated 64KB mailbox region
shared with it's peer for communication. RVU AF has
a separate mailbox region shared with each of RVU PFs
and a RVU PF has a separate region shared with each of
it's VF.

These set of APIs are used by this driver (RVU AF) and
other RVU PF/VF drivers eg netdev, crypto e.t.c.

Signed-off-by: Aleksey Makarov <redacted>
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: Lukasz Bartosik <redacted>

Why does this driver not use the drivers/mailbox/ infrastructure?

This is a common administrative software driver which will be handling requests
from kernel drivers and as well as drivers in userspace applications.
We had to keep mailbox communication infrastructure same across all usages.

Can you explain more about the usage of userspace applications
and what interface you plan to use into the kernel?

Any PCI device here irrespective in what domain (kernel or userspace)
they are in
use common mailbox communication. Which is
# Write a mailbox msg (format is agreed between all parties) into
shared (between AF and other PF/VFs)
   memory region and trigger a interrupt to admin function.
# Admin function processes the msg and puts reply in the same memory
region and trigger
   IRQ to the requesting device. If the device has a driver instance
in kernel then it uses
   IRQ and userspace applications does polling on the IRQ status bit.

Do you things like AF_XDP and virtual machines, or something else?

I meant drivers in DPDK which may or may not use AF_XDP.
And yes if a PCI device is attached to a virtual machine then that
also uses the same mailbox communication.

Sunil.

        Arnd