From: Shawn Jin <shawnxjin@gmail•com>
To: ppcembed <linuxppc-embedded@ozlabs•org>
Subject: Re: Interrupt prioritization on linux for ppc440
Date: Mon, 18 Apr 2005 14:14:23 -0700 [thread overview]
Message-ID: <c3d0340b05041814144133a608@mail.gmail.com> (raw)
In-Reply-To: <20050416005026.GB1086@gate.ebshome.net>
On 4/15/05, Eugene Surovegin <ebs@ebshome•net> wrote:
> I really think that if you need some special higher-priority IRQ
> context you'd better use RTAI or RTLinux. At least, they make clear
> (IIRC) that these IRQ contexts are special.
OK, I'll look into RTAI or RTLinux for priority issue.
> What could be interesting, though, is to to make all 4xx IRQs
> critical, in this case we could use VR to quickly determine which IRQ
> was asserted, instead of current implementation when we use bit
> operations. Not sure, if performance gain is really worth the
> effort :)
If we use VR to determine which IRQ was asserted, it's kind of
reverse. We usually fetch a handler by its IRQ number. It could
require to change irq_desc[] and request_irq().
VR can be calculated automatically provided that VCR is set. What
should be the vector base address? One possible way is similar to the
way how IVPR is set to interrupt_base in head_44x.S but leave the
actual interrupt handler blank, which will be filled in later with a
jump instruction which jumps to the actual ISR once a device driver
request its irq. This means that request_irq() needs to modify kernel
code. Kinda of dangerous, isn't it? This might be part of
infrastructure change you mentioned?
Regards,
-Shawn.
next prev parent reply other threads:[~2005-04-18 21:14 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-15 21:36 Interrupt prioritization on linux for ppc440 Shawn Jin
2005-04-15 22:12 ` Eugene Surovegin
2005-04-15 23:09 ` Shawn Jin
2005-04-16 0:50 ` Eugene Surovegin
2005-04-18 21:14 ` Shawn Jin [this message]
2005-04-18 22:06 ` Eugene Surovegin
2005-04-18 23:11 ` Shawn Jin
2005-04-19 0:27 ` Eugene Surovegin
2005-04-18 17:01 ` Lawrence E. Bakst
2005-04-18 17:25 ` Eugene Surovegin
2005-04-18 20:54 ` Lawrence E. Bakst
2005-04-18 22:27 ` Eugene Surovegin
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