Re: why can't I access to *s->async->data?

From: Edwin du <duq97_at_mails.tsinghua.edu.cn> · Date: Fri, 20 Dec 2002 11:50:00 +0800

My async->data address is 0x0, seems it's not allocated properly.

I'm not sure how can I initialize it. 

In addtion, what is the difference between async->data and
 async->prealloc_buf? prealloc_buf worked but I can't read from my
device file /dev/comedi0.

thanks for replying...

In your mail:
>From:Frank Mori Hess <fmhess_at_users.sourceforge.net>
>Reply-To: 
>To: "Calin A. Culianu" <calin_at_ajvar.org>,
Edwin <duq97_at_mails.tsinghua.edu.cn>
>Subject: Re: why can't I access to *s->async->data?
>
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>
>async->data and async->data_len are gone, due to boards not being able to 
>reliably dma into a user defined buffer.  You have to use async->prealloc_buf 
>and async->prealloc_bufsz.
>
>On Tuesday 17 December 2002 02:54 pm, Calin A. Culianu wrote:
>> Hmm I can't really help you except to suggest that it might be helpful to
>> post an oops message that has been run through ksymoops.  Oops messages
>> are specific to your particular kernel and ksymoops helps a bit with this
>> in that it looks at the kernel symbol table and is able to figure out in
>> which bits of kernel code the crash occured (sometimes this helps).
>>
>> -Calin
>>
>> On Sun, 15 Dec 2002, Edwin wrote:
>> > Dear all:
>> > 	I was trying to write a driver for DI interrupt service,
>> > following structures as comedi_parport.c.
>> > 	The problem is when I access to the s->async->data, system would
>> > break down with a Oops message print out when the interrupt comes.
>
>- -- 
>Frank
>
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