Re: [9fans] usb ohci question

[Philippe Anel <xigh@bouyapop.org>]

Oh, sorry, I forgot that the page-in operation might require an interrupt
from the disk or network controller in order to reload the page.

Phil;

Le 22/02/2011 16:31, Philippe Anel a �crit :
> Hello,
>
> A 'page-in' occurs on page fault exception, which cannot be masked.
>
> Phil;
>
>
> Le 22/02/2011 16:10, rod@hemiola.co.uk a �crit :
>> I'm struggling to understand the ins and outs of the usb ohci driver
>> (usbohci.c) and have a question (well, several).
>>
>> If one writes to an endpoint, then "epio" gets called. This in turn
>> does ilock(ctrl) which disables interrupts on my single-processor
>> machine. Then "epgettd" is called several times to allocate transfer
>> descriptors. Each call to epgettd copies a portion from the user space
>> buffer which was passed as a parameter to "epio".
>>
>> What happens here if the user space buffer is in a page which is not
>> present? Is it possible for a page-in to happen even when interrupts
>> are disabled by the ilock?
>>
>> Thanks for any insight.
>>
>> rod
>>
>>
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