From: Wolfgang Grandegger <wg@domain.hid>
To: Jan Kiszka <jan.kiszka@domain.hid>
Cc: Roderik_Wildenburg@domain.hid, xenomai@xenomai.org
Subject: Re: [Xenomai-help] mmap and secondary mode
Date: Mon, 30 Oct 2006 13:15:50 +0100 [thread overview]
Message-ID: <4545ECF6.1020209@domain.hid> (raw)
In-Reply-To: <45420754.4040907@domain.hid>
Jan Kiszka wrote:
> Roderik_Wildenburg@domain.hid wrote:
>> Just to be sure :
>> Does the access of a mmaped address (real_mmamp of a device file e.g.
>> /dev/dualportmemory) force Xenomai to switch to secondary mode ?
>> I would say yes, as the access of the address probably results into a
>> read/write of the device file.
>> Am I right ?
>
> Depends. If that mapping takes place directly on a physical memory
> region *ahead-of-use*, then you are safe (like with rtdm_iomap_to_user
> from 2.3-devel). But if there is some Linux driver logic in between that
> is triggered via page faults on access to those memory blocks, this is
> certainly indeterministic. Probably easy to find out by analysing the
> Linux driver in question /wrt its mapping code.
But it should be save to call the driver's mmap function in secondary
mode (init code) and use the virtual address later on in primary mode.
Wolfgang.
prev parent reply other threads:[~2006-10-30 12:15 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-27 9:13 [Xenomai-help] mmap and secondary mode Roderik_Wildenburg
2006-10-27 13:19 ` Jan Kiszka
2006-10-30 12:15 ` Wolfgang Grandegger [this message]
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=4545ECF6.1020209@domain.hid \
--to=wg@domain.hid \
--cc=Roderik_Wildenburg@domain.hid \
--cc=jan.kiszka@domain.hid \
--cc=xenomai@xenomai.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.