Re: [PATCH v2 2/3] fpga manager: framework core

[One Thousand Gnomes]

On Sat, 6 Dec 2014 13:00:17 +0000
Grant Likely <grant.likely@xxxxxxxxxx> wrote:

> On Fri, Oct 24, 2014 at 11:52 AM, Pavel Machek <pavel@xxxxxxx> wrote:
> > Hi!
> >
> >> * /sys/class/fpga_manager/<fpga>/firmware
> >>   Name of FPGA image file to load using firmware class.
> >>   $ echo image.rbf > /sys/class/fpga_manager/<fpga>/firmware
> >
> > I .. still don't think this is good idea. What about namespaces?
> > The path corresponds to path in which namespace?
> 
> I don't understand your concern here. This allows userspace to name
> the FPGA bitstream that the kernel will use during request_firmware(),
> and it will show up as the $FIRMWARE value in the uevent file, but it
> is still the responsibility of userspace to choose what to load, and
> it can freely ignore the setting of $FIRMWARE if it needs to.

I think the entire model here is basically pedicated on a bogus
assumption that an FPGA is a one shot device. It's not. It's a fast
reloadable reusable device. A lot of work being done with FPGAs in
operating systems already involves basically task switching and
scheduling FPGAs as a shared resource pool. Trying to nail something
together with request_firmware is several years behind the curve.

>From userspace it needs to be a open, load, use, close type model, not a
static or semi-static pile of mappings.

Alan
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