From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Thu, 20 Sep 2012 13:06:38 +0200
From: Philippe Gerum <rpm@xenomai.org>
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Subject: Re: [Xenomai] [PATCH] Revert "ipipe: ipipe_request_irq(),
 ipipe_free_irq() are root-only services"
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To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: "Mauerer, Wolfgang" <wolfgang.mauerer@siemens.com>, Xenomai <xenomai@xenomai.org>

On 09/20/2012 12:57 PM, Jan Kiszka wrote:
> On 2012-09-20 12:56, Jan Kiszka wrote:
>> On 2012-09-20 12:49, Philippe Gerum wrote:
>>> On 09/20/2012 12:37 PM, Jan Kiszka wrote:
>>>> This reverts commit 073ff1e8045d0311b8cf390687c0ba3619681672.
>>>>
>>>> Both service are NOT just root-only services. E.g., rtdm_irq_request
>>>> requires by specification support also over non-Linux contexts.
>>>
>>> Nack. We can't run the enable code for MSIs over non-root, and
>>> that code typically follows the irq request. Besides, we want to mask
>>> the source upon irq free to handle the SMP case properly, which we could
>>> not do from non-root with MSIs.
>>>
>>> So either we have both request+enable and free usable over non-root, or
>>> there is no point.
>>
>> OK, I get the point with legacy MSI. Then we have two other bugs to solve:
>>  - in I-pipe as it holds a hardened spin lock across enable/disable (of
>>    MSIs)

Missed it. Where?

>>  - in Xenomai 2.6 (at least, didn't check forge) as it calls with a
>>    hardened spin lock held into ipipe_virtualize_irq
> 
> Sorry, three bugs:
>  - in the RTDM spec as it always allowed rtdm_irq_request over RT task
>    contexts
>

Yes. This was likely designed when ->enable/disable() handlers would not
traverse a whole pile of hairy code highly dependent on the PCI
infrastructure like today. And on the ppc side, this is not getting any
prettier.

> Jan
> 


-- 
Philippe.