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List:       linux-arm-kernel
Subject:    Re: why cannot block inside interrupt context
From:       li xinyi <lxinyi () gmail ! com>
Date:       2005-01-30 23:56:34
Message-ID: d6a30f3205013015564e7970df () mail ! gmail ! com
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Hi,

Thanks for answering this stupid question. :)

What exactly is "kernel control path has process context" defined? In
terms of ARM kernel, interrupts are actually handled inside the SVC
mode (__irq_usr or __irq_svc), where we have sp_SVC point to
task_union of process being interrupted. Doesnt this mean that the
contorl path has the process context? This really confuses me.

Thanks,
Li


On Fri, 28 Jan 2005 21:52:48 +0100, Rainer Weikusat
<rainer.weikusat@sncag.com> wrote:
> 
> Because you *cannot* sleep inside the handler. That would refer to
> telling the kernel to schedule some other process instead of the
> process on whose behalf your kernel code is running and there is no
> such process. As soon as your handler is no longer running, it's
> 'context' is gone. There is no way for the kernel to come back after
> 'some time' has elapsed. And there is no point in asking why this is
> so, because that's how the implementation works.
>

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