From: Nick Garnett <nickg@cygnus.co.uk>
To: ecos-discuss@sourceware.cygnus.com
Subject: Re: [ECOS] nested interrupts
Date: Thu, 18 Jan 2001 05:46:00 -0000 [thread overview]
Message-ID: <wwgsnmh2dih.fsf@balti.cambridge.redhat.com> (raw)
In-Reply-To: <002f01c0814d$d618fa80$6f2314ac@realtek.com.tw>
"Xavier Wang" <xavierwang@ms19.url.com.tw> writes:
> Thanks, Jesper.
>
> One more question. By looking into the source code, I still can't
> figure out that why DSRs can call most kernel functions but
> ISRs can't. Is it the stack problem or scheduler locking problem
> or something else?
The kernel does not block interrupts during critical sections, so an
ISR can occur at any point, even while the scheduler is manipulating
the run queues. If the ISR then tries to manipulate the same data
structures, by calling a kernel function, then they will be
corrupted. Hence the use of DSRs to defer these calls until the data
structures are in a consistent state.
--
Nick Garnett, eCos Kernel Architect
Red Hat, Cambridge, UK
next prev parent reply other threads:[~2001-01-18 5:46 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-01-17 23:51 Xavier Wang
2001-01-18 1:03 ` Jesper Skov
2001-01-18 4:15 ` Xavier Wang
2001-01-18 5:00 ` Nick Garnett
2001-01-18 4:59 ` Xavier Wang
2001-01-18 5:46 ` Nick Garnett [this message]
2001-01-18 21:52 ` Xavier Wang
2001-01-18 22:35 ` Jonathan Larmour
2001-01-18 8:26 ` Sergei Slobodov
2001-01-18 20:56 ` Xavier Wang
2001-01-18 22:37 ` Jonathan Larmour
-- strict thread matches above, loose matches on Subject: below --
2000-09-11 0:03 [ECOS] Nested Interrupts Sandeep Rikhi
2000-09-11 7:53 ` Jonathan Larmour
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