* Status of ARM FIQ?
@ 2013-09-30 18:48 Bird, Tim
2013-09-30 20:46 ` Florian Fainelli
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Bird, Tim @ 2013-09-30 18:48 UTC (permalink / raw)
To: linux-arm-kernel
I'm working through some proposals for contract work for the Consumer
Electronics Workgroup, and one of them involves use of ARM FIQ
as a debug activator. I have heard a rumor that FIQ mode is not being
included in some modern ARM CPUs.
Is there any truth to this? Can someone give me a pointer to information
about this?
Thanks,
-- Tim
^ permalink raw reply [flat|nested] 6+ messages in thread
* Status of ARM FIQ?
2013-09-30 18:48 Status of ARM FIQ? Bird, Tim
@ 2013-09-30 20:46 ` Florian Fainelli
2013-10-01 7:07 ` Uwe Kleine-König
2013-10-01 9:26 ` Dave Martin
2 siblings, 0 replies; 6+ messages in thread
From: Florian Fainelli @ 2013-09-30 20:46 UTC (permalink / raw)
To: linux-arm-kernel
Le lundi 30 septembre 2013 20:48:15 Bird, Tim a ?crit :
> I'm working through some proposals for contract work for the Consumer
> Electronics Workgroup, and one of them involves use of ARM FIQ
> as a debug activator. I have heard a rumor that FIQ mode is not being
> included in some modern ARM CPUs.
>
> Is there any truth to this? Can someone give me a pointer to information
> about this?
What are these modern ARM CPUs? The 3 ARMv7 (A, R, M) and ARMv8 have FIQ.
--
Florian
^ permalink raw reply [flat|nested] 6+ messages in thread
* Status of ARM FIQ?
2013-09-30 18:48 Status of ARM FIQ? Bird, Tim
2013-09-30 20:46 ` Florian Fainelli
@ 2013-10-01 7:07 ` Uwe Kleine-König
2013-10-01 9:26 ` Dave Martin
2 siblings, 0 replies; 6+ messages in thread
From: Uwe Kleine-König @ 2013-10-01 7:07 UTC (permalink / raw)
To: linux-arm-kernel
Hello Tim,
On Mon, Sep 30, 2013 at 08:48:15PM +0200, Bird, Tim wrote:
> I'm working through some proposals for contract work for the Consumer
> Electronics Workgroup, and one of them involves use of ARM FIQ
> as a debug activator. I have heard a rumor that FIQ mode is not being
> included in some modern ARM CPUs.
>
> Is there any truth to this? Can someone give me a pointer to information
> about this?
The ARMv7-M doesn't have an FIQ.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-K?nig |
Industrial Linux Solutions | http://www.pengutronix.de/ |
^ permalink raw reply [flat|nested] 6+ messages in thread
* Status of ARM FIQ?
2013-09-30 18:48 Status of ARM FIQ? Bird, Tim
2013-09-30 20:46 ` Florian Fainelli
2013-10-01 7:07 ` Uwe Kleine-König
@ 2013-10-01 9:26 ` Dave Martin
2013-10-01 16:04 ` Bird, Tim
2 siblings, 1 reply; 6+ messages in thread
From: Dave Martin @ 2013-10-01 9:26 UTC (permalink / raw)
To: linux-arm-kernel
On Mon, Sep 30, 2013 at 08:48:15PM +0200, Bird, Tim wrote:
> I'm working through some proposals for contract work for the Consumer
> Electronics Workgroup, and one of them involves use of ARM FIQ
> as a debug activator. I have heard a rumor that FIQ mode is not being
> included in some modern ARM CPUs.
>
> Is there any truth to this? Can someone give me a pointer to information
> about this?
All CPUs implement FIQ, except for the M-class CPUS in v7 onwards (which
don't have an MMU, and thus could only run ucLinux).
As to whether you can use FIQ, "it depends":
Since the introduction of the Security Extensions in v6Z / v7,
FIQ can be repurposed as a private interrupt for the Secure World, so
if there is resident Secure World software, it may be impossible for
Linux to use FIQ.
Whether this does or doesn't apply depends on the SoC, and on how
it has been integrated and set up. Consumer device SoCs, especially
anything coming to you via a mobile provider, will likely have this
restriction. Dev boards may be a bit more relaxed.
John Stultz has been working on the FIQ debugger for Android and may
have some ideas.
I believe that the Virtualisation extensions allow virtual FIQs to be
delivered to the guest, so that KVM could send fake FIQs to guests even
if the KVM host cannot itself use FIQ. I'm a bit hazy on this though,
and haven't played with it.
Cheers
---Dave
^ permalink raw reply [flat|nested] 6+ messages in thread
* Status of ARM FIQ?
2013-10-01 9:26 ` Dave Martin
@ 2013-10-01 16:04 ` Bird, Tim
2013-10-01 16:21 ` John Stultz
0 siblings, 1 reply; 6+ messages in thread
From: Bird, Tim @ 2013-10-01 16:04 UTC (permalink / raw)
To: linux-arm-kernel
On Tuesday, October 01, 2013 2:26 AM, Dave Martin [Dave.Martin at arm.com] wrote:
>On Mon, Sep 30, 2013 at 08:48:15PM +0200, Bird, Tim wrote:
>> I'm working through some proposals for contract work for the Consumer
>> Electronics Workgroup, and one of them involves use of ARM FIQ
>> as a debug activator. I have heard a rumor that FIQ mode is not being
>> included in some modern ARM CPUs.
>>
>> Is there any truth to this? Can someone give me a pointer to information
>> about this?
>
>All CPUs implement FIQ, except for the M-class CPUS in v7 onwards (which
>don't have an MMU, and thus could only run ucLinux).
>
>
>As to whether you can use FIQ, "it depends":
>
>Since the introduction of the Security Extensions in v6Z / v7,
>FIQ can be repurposed as a private interrupt for the Secure World, so
>if there is resident Secure World software, it may be impossible for
>Linux to use FIQ.
>
>Whether this does or doesn't apply depends on the SoC, and on how
>it has been integrated and set up. Consumer device SoCs, especially
>anything coming to you via a mobile provider, will likely have this
>restriction. Dev boards may be a bit more relaxed.
Ahh. This is exactly the information I was looking for. I think
this is what I heard about, but I mangled it in my mind. (It was several
months ago that I heard something along these lines.)
>John Stultz has been working on the FIQ debugger for Android and may
>have some ideas.
The CE WG is considering sponsoring some work on the FIQ debugger, and
some Sony teams are still very interested in this getting mainlined all the way.
(though not the mobile phone team, for the reasons you mention - I'm pretty sure
that FIQ is not available to us in that product segment.)
Thanks very much for the info (to all who responded).
John,
Do you know the status of this? Wasn't Anton Vorontsov working on this last year?
Does anyone know what the current status of that is?
-- Tim
^ permalink raw reply [flat|nested] 6+ messages in thread
* Status of ARM FIQ?
2013-10-01 16:04 ` Bird, Tim
@ 2013-10-01 16:21 ` John Stultz
0 siblings, 0 replies; 6+ messages in thread
From: John Stultz @ 2013-10-01 16:21 UTC (permalink / raw)
To: linux-arm-kernel
On 10/01/2013 09:04 AM, Bird, Tim wrote:
> On Tuesday, October 01, 2013 2:26 AM, Dave Martin [Dave.Martin at arm.com] wrote:
>> John Stultz has been working on the FIQ debugger for Android and may
>> have some ideas.
> The CE WG is considering sponsoring some work on the FIQ debugger, and
> some Sony teams are still very interested in this getting mainlined all the way.
> (though not the mobile phone team, for the reasons you mention - I'm pretty sure
> that FIQ is not available to us in that product segment.)
>
> Thanks very much for the info (to all who responded).
>
> John,
>
> Do you know the status of this? Wasn't Anton Vorontsov working on this last year?
> Does anyone know what the current status of that is?
Right, Anton was working on enabling an FIQ mode kdb (along with
modifications to kdb to provide a safe kiosk mode), in order to replace
Android's FIQ debugger. The patches were sent to the lists and various
maintainers a number of times to almost no response. Sadly for us, Anton
went back to school, so the effort has stalled.
I tried to resubmit the patches (without deeply understanding them), but
again it didn't seem to get maintainer interest and the few questions
that did arise I wasn't able to answer effectively.
Its still on our todo list, and I'd love to see some progress on it, but
I just haven't been able to commit the time myself.
If anyone wants to take a look at it, Anton's work can be found here:
FIQ KDB:
git://git.linaro.org/people/jstultz/android-dev.git dev/fiq-kdb
https://git.linaro.org/gitweb?p=people/jstultz/android-dev.git;a=shortlog;h=refs/heads/dev/fiq-kdb
KDB Kiosk:
git://git.linaro.org/people/jstultz/android-dev.git dev/kdb-kiosk
https://git.linaro.org/gitweb?p=people/jstultz/android-dev.git;a=shortlog;h=refs/heads/dev/kdb-kiosk
It would be interesting to also hear feedback as to how close Anton's
kdb approach is to what you're thinking of trying to push upstream.
thanks
-john
^ permalink raw reply [flat|nested] 6+ messages in thread
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2013-09-30 18:48 Status of ARM FIQ? Bird, Tim
2013-09-30 20:46 ` Florian Fainelli
2013-10-01 7:07 ` Uwe Kleine-König
2013-10-01 9:26 ` Dave Martin
2013-10-01 16:04 ` Bird, Tim
2013-10-01 16:21 ` John Stultz
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