From: Philippe Anel <xigh@bouyapop.org>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] usb ohci question
Date: Tue, 22 Feb 2011 16:31:32 +0100 [thread overview]
Message-ID: <4D63D6D4.5040808@bouyapop.org> (raw)
In-Reply-To: <20110222151218.4A02965D3E@server.hemiola.co.uk>
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
>
>
next prev parent reply other threads:[~2011-02-22 15:31 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-22 15:10 rod
2011-02-22 15:30 ` Francisco J Ballesteros
2011-02-22 16:42 ` rod
2011-02-22 16:50 ` Francisco J Ballesteros
2011-02-22 15:31 ` Philippe Anel [this message]
2011-02-22 15:45 ` Philippe Anel
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4D63D6D4.5040808@bouyapop.org \
--to=xigh@bouyapop.org \
--cc=9fans@9fans.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).