RE: [ECOS] FW: Questions about dsr?

RE: [ECOS] FW: Questions about dsr?

[Retallack, Mark (Poole)]

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DSR's cannot block. (We learnt the hard way after a very strange crash and
not reading the documentation). A DSR is just a delayed ISR, so you don't
want to be doing to much in a DSR that cannot be done in a thread. 
 
 -----Original Message-----
From: Wang.Alvin@iac.com.tw [mailto:Wang.Alvin@iac.com.tw]
Sent: 17 April 2003 05:11
To: ecos-discuss@sources.redhat.com
Subject: [ECOS] FW: Questions about dsr?




Hi to all, 

I have some questions about DSR as following… 

1.Can DSR waits on semphore? 
2.If one DSR is blocked, can kernel switch to another DSR? 

Thank you for answering these question. 

Alvin Wang 



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Re: [ECOS] FW: Questions about dsr?

[Bart Veer]

>>>>> "Alvin" ==   <Wang.Alvin@iac.com.tw> writes:

    >> Hi to all,
    >> 
    >> I have some questions about DSR as following
    >>
    >> 1.Can DSR waits on semphore?

No.

    >> 2.If one DSR is blocked, can kernel switch to another DSR?

No. A DSR must run to completion before the next DSR is run, or before
control returns to a thread, although interrupts are allowed while a
DSR is running.

For more information see the kernel documentation,
http://sources.redhat.com/ecos/docs-latest/ref/kernel-overview.html
especially the sections on "Threads and Interrupt Handling" and
"Calling Contexts".

Bart

-- 
Bart Veer                       eCos Configuration Architect
http://www.ecoscentric.com/     The eCos and RedBoot experts

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[ECOS] FW: Questions about dsr?

[Wang.Alvin]

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> Hi to all,
> 
> I have some questions about DSR as following…
> 
> 1.Can DSR waits on semphore?
> 2.If one DSR is blocked, can kernel switch to another DSR?
> 
> Thank you for answering these question.
> 
> Alvin Wang

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