[Ksummit-discuss] [TECH TOPIC] FPGAs and how to program them from kernel

[Ksummit-discuss] [TECH TOPIC] FPGAs and how to program them from kernel

[Pavel Machek]

Hi!

(Please cc me on replies)

FPGAs are common in embedded systems, where they can provide missing
hardware interfaces, directly implement functionality, or provide
custom hardware modules. These days they become available for servers,
too, where they can act as high-performance co-processors (which are
tricky to program).

There are very different requirements for FPGA that implements your
SATA controller (so you need it for boot), and one where multiple
userland applications directly access FPGA using it for different
computations, needing FPGA netlist to be changed based on userspace
needs. Yet, it would be nice to come up with single interface that can
handle all the different applications, and is suitable for mainline
kernel.

People that might be interested:

Michal Simek <michal.simek@xilinx.com>
Dinh Nguyen <dinguyen@opensource.altera.com>
<atull@opensource.altera.com>
Steffen Trumtrar <s.trumtrar@pengutronix.de>
Marek Vasut <marex@denx.de>
Alan Cox


									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [Ksummit-discuss] [TECH TOPIC] FPGAs and how to program them from kernel

[Linus Walleij]

On Thu, Jul 23, 2015 at 12:57 PM, Pavel Machek <pavel@ucw.cz> wrote:


> FPGAs are common in embedded systems, where they can provide missing
> hardware interfaces, directly implement functionality, or provide
> custom hardware modules. These days they become available for servers,
> too, where they can act as high-performance co-processors (which are
> tricky to program).
>
> People that might be interested:

Alan Tull <atull@altera.com>
Is sending patchsets for this, and would be the primary person to
invite for this topic:
http://marc.info/?l=linux-kernel&m=143714949226387&w=2

Yours,
Linus Walleij

Re: [Ksummit-discuss] [TECH TOPIC] FPGAs and how to program them from kernel

[Pavel Machek]

On Thu 2015-07-23 13:26:32, Linus Walleij wrote:
> On Thu, Jul 23, 2015 at 12:57 PM, Pavel Machek <pavel@ucw.cz> wrote:
> 
> 
> > FPGAs are common in embedded systems, where they can provide missing
> > hardware interfaces, directly implement functionality, or provide
> > custom hardware modules. These days they become available for servers,
> > too, where they can act as high-performance co-processors (which are
> > tricky to program).
> >
> > People that might be interested:
> 
> Alan Tull <atull@altera.com>
> Is sending patchsets for this, and would be the primary person to
> invite for this topic:
> http://marc.info/?l=linux-kernel&m=143714949226387&w=2

Actually, I had him in my original email, but without full name.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [Ksummit-discuss] [TECH TOPIC] FPGAs and how to program them from kernel

[Linus Walleij]

On Thu, Jul 23, 2015 at 2:10 PM, Pavel Machek <pavel@denx.de> wrote:
> On Thu 2015-07-23 13:26:32, Linus Walleij wrote:
>> On Thu, Jul 23, 2015 at 12:57 PM, Pavel Machek <pavel@ucw.cz> wrote:
>>
>>
>> > FPGAs are common in embedded systems, where they can provide missing
>> > hardware interfaces, directly implement functionality, or provide
>> > custom hardware modules. These days they become available for servers,
>> > too, where they can act as high-performance co-processors (which are
>> > tricky to program).
>> >
>> > People that might be interested:
>>
>> Alan Tull <atull@altera.com>
>> Is sending patchsets for this, and would be the primary person to
>> invite for this topic:
>> http://marc.info/?l=linux-kernel&m=143714949226387&w=2
>
> Actually, I had him in my original email, but without full name.
>                                                                         Pavel

Do you mean this:

On Thu, Jul 23, 2015 at 12:57 PM, Pavel Machek <pavel@ucw.cz> wrote:

> Alan Cox

;)

(Happens easily, Linus Torvalds asked me to change my name
to avoid confusion...)

Yours,
Linus Walleij

Re: [Ksummit-discuss] [TECH TOPIC] FPGAs and how to program them from kernel

[Christoph Lameter]

On Thu, 23 Jul 2015, Linus Walleij wrote:

> >> > People that might be interested:

I would be very very interested in the subject matter. Anything that helps
creating some abstraction layer that allows the open source development of
tools on top.

Re: [Ksummit-discuss] [TECH TOPIC] FPGAs and how to program them from kernel

[atull]

On Thu, 23 Jul 2015, Christoph Lameter wrote:

> On Thu, 23 Jul 2015, Linus Walleij wrote:
> 
> > >> > People that might be interested:
> 
> I would be very very interested in the subject matter. Anything that helps
> creating some abstraction layer that allows the open source development of
> tools on top.
> 
> _______________________________________________
> Ksummit-discuss mailing list
> Ksummit-discuss@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/ksummit-discuss
> 

Jason is another person who may be interested in this topic:
Jason Gunthorpe = jgunthorpe at obsidianresearch.com

My work has been to get a uniform API for FPGA programming into the
kernel along with an interface for controlling reprogramming.  My
current patchset separates the two so that if the interface I am
proposing doesn't meet somebody's use needs, another interface
can be written to use the API functions.

http://marc.info/?l=linux-kernel&m=143714949226387&w=2

Topics that have been discussed in the mailing list could be included 
here:

 * At least two different basic use models:
   * FPGA as hardware (containing harware devices that need drivers)
   * FPGA as accelerator.  If FPGA is an accelerator, it could be
     allocated in a malloc-like thing - Alan Cox's proposal.
 * Device Tree Overlays as an interface in the "FPGA as Hardware" use,
   where loading an overlay will cause FPGA reconfiguration, bridges
   getting enabled, and devices being created, drivers probed.  The
   code for accomplishing all this is actually quite small.
 * Some use cases are complicated systems that need a lot of userspace
   to bring things up in a sequenced way (may need another interface
   with lots of userspace control and FPGA status available to
   userspace).
 * Security issues that arise if FPGA programming can be controlled
   from userspace.
 * How to control the bridges. Some hardware needs the bridges disabled
   during FPGA programming.  How to conceptualize this in the device tree.
 * It is likely that these different use cases will best be suited by
   different interfaces.

Alan Tull

atull at opensource.altera.com is a good email for me for mailing
list purposes (to avoid Outlook).

Re: [Ksummit-discuss] [TECH TOPIC] FPGAs and how to program them from kernel

[Michal Simek]

[-- Attachment #1: Type: text/plain, Size: 2697 bytes --]

On 07/23/2015 11:20 PM, atull wrote:
> On Thu, 23 Jul 2015, Christoph Lameter wrote:
> 
>> On Thu, 23 Jul 2015, Linus Walleij wrote:
>>
>>>>>> People that might be interested:
>>
>> I would be very very interested in the subject matter. Anything that helps
>> creating some abstraction layer that allows the open source development of
>> tools on top.
>>
>> _______________________________________________
>> Ksummit-discuss mailing list
>> Ksummit-discuss@lists.linuxfoundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/ksummit-discuss
>>
> 
> Jason is another person who may be interested in this topic:
> Jason Gunthorpe = jgunthorpe at obsidianresearch.com
> 
> My work has been to get a uniform API for FPGA programming into the
> kernel along with an interface for controlling reprogramming.  My
> current patchset separates the two so that if the interface I am
> proposing doesn't meet somebody's use needs, another interface
> can be written to use the API functions.
> 
> http://marc.info/?l=linux-kernel&m=143714949226387&w=2
> 
> Topics that have been discussed in the mailing list could be included 
> here:
> 
>  * At least two different basic use models:
>    * FPGA as hardware (containing harware devices that need drivers)
>    * FPGA as accelerator.  If FPGA is an accelerator, it could be
>      allocated in a malloc-like thing - Alan Cox's proposal.
>  * Device Tree Overlays as an interface in the "FPGA as Hardware" use,
>    where loading an overlay will cause FPGA reconfiguration, bridges
>    getting enabled, and devices being created, drivers probed.  The
>    code for accomplishing all this is actually quite small.
>  * Some use cases are complicated systems that need a lot of userspace
>    to bring things up in a sequenced way (may need another interface
>    with lots of userspace control and FPGA status available to
>    userspace).
>  * Security issues that arise if FPGA programming can be controlled
>    from userspace.
>  * How to control the bridges. Some hardware needs the bridges disabled
>    during FPGA programming.  How to conceptualize this in the device tree.
>  * It is likely that these different use cases will best be suited by
>    different interfaces.

user space part is probably the most problematic topic which needs to be
discussed.

Thanks,
Michal

-- 
Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/
Maintainer of Linux kernel - Xilinx Zynq ARM architecture
Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform



[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 198 bytes --]

Re: [Ksummit-discuss] [TECH TOPIC] FPGAs and how to program them from kernel

[Pavel Machek]

On Thu 2015-07-23 15:25:53, Christoph Lameter wrote:
> On Thu, 23 Jul 2015, Linus Walleij wrote:
> 
> > >> > People that might be interested:
> 
> I would be very very interested in the subject matter. Anything that helps
> creating some abstraction layer that allows the open source development of
> tools on top.

Which tools would be that?

So far we have netlists in .rbf format, and open source code to load
them to the FPGA.

Unfortunately, VHDL to .rbf compiler is not open source. (But it would
be great to have one). What other tools are important in this area?

Best regards,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [Ksummit-discuss] [TECH TOPIC] FPGAs and how to program them from kernel

[Christoph Lameter]

On Tue, 28 Jul 2015, Pavel Machek wrote:

> Which tools would be that?

FPGA firmware upload. Up/down. State determinations etc? Administrative
tasks first. Lets do easy low hanging fruit first.

That way one can write scripts / tools to administer FPGAs from different
manufacturers with the same commands.

Re: [Ksummit-discuss] [TECH TOPIC] FPGAs and how to program them from kernel

[atull]

On Tue, 28 Jul 2015, Christoph Lameter wrote:

> On Tue, 28 Jul 2015, Pavel Machek wrote:
> 
> > Which tools would be that?
> 
> FPGA firmware upload. Up/down. State determinations etc? Administrative
> tasks first. Lets do easy low hanging fruit first.

Exactly what my patchset is intended to do.

Alan Tull

> 
> That way one can write scripts / tools to administer FPGAs from different
> manufacturers with the same commands.
> 
> _______________________________________________
> Ksummit-discuss mailing list
> Ksummit-discuss@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/ksummit-discuss
> 

Re: [Ksummit-discuss] [TECH TOPIC] FPGAs and how to program them from kernel

[Alan Tull]

I've been working on the patchset for this.  I nominate myself.

Alan Tull

On Tue, Jul 28, 2015 at 12:34 PM, atull <atull@opensource.altera.com> wrote:
> On Tue, 28 Jul 2015, Christoph Lameter wrote:
>
>> On Tue, 28 Jul 2015, Pavel Machek wrote:
>>
>> > Which tools would be that?
>>
>> FPGA firmware upload. Up/down. State determinations etc? Administrative
>> tasks first. Lets do easy low hanging fruit first.
>
> Exactly what my patchset is intended to do.
>
> Alan Tull
>
>>
>> That way one can write scripts / tools to administer FPGAs from different
>> manufacturers with the same commands.
>>
>> _______________________________________________
>> Ksummit-discuss mailing list
>> Ksummit-discuss@lists.linuxfoundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/ksummit-discuss
>>
> _______________________________________________
> Ksummit-discuss mailing list
> Ksummit-discuss@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/ksummit-discuss

Re: [Ksummit-discuss] [TECH TOPIC] FPGAs and how to program them from kernel

[Pavel Machek]

On Thu 2015-07-23 15:00:57, Linus Walleij wrote:
> On Thu, Jul 23, 2015 at 2:10 PM, Pavel Machek <pavel@denx.de> wrote:
> > On Thu 2015-07-23 13:26:32, Linus Walleij wrote:
> >> On Thu, Jul 23, 2015 at 12:57 PM, Pavel Machek <pavel@ucw.cz> wrote:
> >>
> >>
> >> > FPGAs are common in embedded systems, where they can provide missing
> >> > hardware interfaces, directly implement functionality, or provide
> >> > custom hardware modules. These days they become available for servers,
> >> > too, where they can act as high-performance co-processors (which are
> >> > tricky to program).
> >> >
> >> > People that might be interested:
> >>
> >> Alan Tull <atull@altera.com>
> >> Is sending patchsets for this, and would be the primary person to
> >> invite for this topic:
> >> http://marc.info/?l=linux-kernel&m=143714949226387&w=2
> >
> > Actually, I had him in my original email, but without full name.
> >                                                                         Pavel
> 
> Do you mean this:
> 
> On Thu, Jul 23, 2015 at 12:57 PM, Pavel Machek <pavel@ucw.cz> wrote:
> 
> > Alan Cox
> 
> ;)

Yes, happens easily, but did not happen this time:

> <atull@opensource.altera.com>
> Steffen Trumtrar <s.trumtrar@pengutronix.de>
> Marek Vasut <marex@denx.de>
> Alan Cox

:-).

> (Happens easily, Linus Torvalds asked me to change my name
> to avoid confusion...)

Hmm, at one point, I had both real Linus Torvalds and fake Linus
Torvalds on the cc list. And fake one tried helping me debugging
graphics problems. It was weird.

								Pavel

--
(english)
http://www.livejournal.com/~pavelmachek (cesky, pictures)
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [Ksummit-discuss] [TECH TOPIC] FPGAs and how to program them from kernel

[Andy Lutomirski]

[cc: CASPER]

On Thu, Jul 23, 2015 at 4:26 AM, Linus Walleij <linus.walleij@linaro.org> wrote:
> On Thu, Jul 23, 2015 at 12:57 PM, Pavel Machek <pavel@ucw.cz> wrote:
>
>
>> FPGAs are common in embedded systems, where they can provide missing
>> hardware interfaces, directly implement functionality, or provide
>> custom hardware modules. These days they become available for servers,
>> too, where they can act as high-performance co-processors (which are
>> tricky to program).
>>
>> People that might be interested:
>
> Alan Tull <atull@altera.com>
> Is sending patchsets for this, and would be the primary person to
> invite for this topic:
> http://marc.info/?l=linux-kernel&m=143714949226387&w=2

I'm adding the CASPER list to see if anyone is interested.  CASPER is
a big Berkeley-based project that, among other things, designs
powerful programmable boards with PowerPC CPUs running Linux and giant
FPGAs for signal processing and I/O.

https://casper.berkeley.edu/wiki/ROACH2

I haven't used ROACH2, but I've used ROACH a bunch, and it would be
really nice if there was a standard Linux API for dealing with FPGAs.

--Andy

Re: [Ksummit-discuss] [TECH TOPIC] FPGAs and how to program them from kernel

[H. Peter Anvin]

On 07/23/2015 03:57 AM, Pavel Machek wrote:
> Hi!
> 
> (Please cc me on replies)
> 
> FPGAs are common in embedded systems, where they can provide missing
> hardware interfaces, directly implement functionality, or provide
> custom hardware modules. These days they become available for servers,
> too, where they can act as high-performance co-processors (which are
> tricky to program).
> 
> There are very different requirements for FPGA that implements your
> SATA controller (so you need it for boot), and one where multiple
> userland applications directly access FPGA using it for different
> computations, needing FPGA netlist to be changed based on userspace
> needs. Yet, it would be nice to come up with single interface that can
> handle all the different applications, and is suitable for mainline
> kernel.
> 
> People that might be interested:
> 
> Michal Simek <michal.simek@xilinx.com>
> Dinh Nguyen <dinguyen@opensource.altera.com>
> <atull@opensource.altera.com>
> Steffen Trumtrar <s.trumtrar@pengutronix.de>
> Marek Vasut <marex@denx.de>
> Alan Cox
> 

Definitely add me to that list.

	-hpa

Re: [Ksummit-discuss] [TECH TOPIC] FPGAs and how to program them from kernel

[Laurent Pinchart]

On Thursday 23 July 2015 12:57:11 Pavel Machek wrote:
> Hi!
> 
> (Please cc me on replies)
> 
> FPGAs are common in embedded systems, where they can provide missing
> hardware interfaces, directly implement functionality, or provide
> custom hardware modules. These days they become available for servers,
> too, where they can act as high-performance co-processors (which are
> tricky to program).
> 
> There are very different requirements for FPGA that implements your
> SATA controller (so you need it for boot), and one where multiple
> userland applications directly access FPGA using it for different
> computations, needing FPGA netlist to be changed based on userspace
> needs. Yet, it would be nice to come up with single interface that can
> handle all the different applications, and is suitable for mainline
> kernel.
> 
> People that might be interested:
> 
> Michal Simek <michal.simek@xilinx.com>
> Dinh Nguyen <dinguyen@opensource.altera.com>
> <atull@opensource.altera.com>
> Steffen Trumtrar <s.trumtrar@pengutronix.de>
> Marek Vasut <marex@denx.de>
> Alan Cox

I've been working on V4L2 drivers for Xilinx FPGAs and I'm interested in this 
topic from that point of view. I see interactions with userspace being one of 
the most complex part, both in terms of triggering the reprogramming 
operations and handling applications that actively use the FPGA resources.

-- 
Regards,

Laurent Pinchart

Re: [Ksummit-discuss] [TECH TOPIC] FPGAs and how to program them from kernel

[Benjamin Herrenschmidt]

On Thu, 2015-07-23 at 12:57 +0200, Pavel Machek wrote:
> Hi!
> 
> (Please cc me on replies)
> 
> FPGAs are common in embedded systems, where they can provide missing
> hardware interfaces, directly implement functionality, or provide
> custom hardware modules. These days they become available for servers,
> too, where they can act as high-performance co-processors (which are
> tricky to program).
> 
> There are very different requirements for FPGA that implements your
> SATA controller (so you need it for boot), and one where multiple
> userland applications directly access FPGA using it for different
> computations, needing FPGA netlist to be changed based on userspace
> needs. Yet, it would be nice to come up with single interface that can
> handle all the different applications, and is suitable for mainline
> kernel.

I am interested as well. POWER has this thing called "CAPI" for coherent
accelerators which is essentially FPGA based. It allows you to design an
FPGA solution that is both cache coherent (ie, can hold cache lines
locally) and has an MMU allowing to operate within a user space context.

We have been developing interfaces for that in Linux but mostly as a
specific driver, it might be worthwhile seeing whether there are any
commonalities.

Ben.

> People that might be interested:
> 
> Michal Simek <michal.simek@xilinx.com>
> Dinh Nguyen <dinguyen@opensource.altera.com>
> <atull@opensource.altera.com>
> Steffen Trumtrar <s.trumtrar@pengutronix.de>
> Marek Vasut <marex@denx.de>
> Alan Cox
> 
> 
> 									Pavel