From: Arnd Hannemann <arnd@arndnet.de>
To: Francis Moreau <francis.moro@gmail.com>
Cc: "linux-os (Dick Johnson)" <linux-os@analogic.com>,
linux-kernel@vger.kernel.org
Subject: Re: How to avoid data copies in a driver ?
Date: Thu, 15 May 2008 13:50:27 +0200 [thread overview]
Message-ID: <482C2383.5070206@arndnet.de> (raw)
In-Reply-To: <38b2ab8a0805150040s6933de14p7c2014945ba0810d@mail.gmail.com>
Francis Moreau wrote:
> Hello,
>
> On Wed, May 14, 2008 at 11:23 PM, linux-os (Dick Johnson)
> <linux-os@analogic.com> wrote:
>> You memory-map the data. Impliment mmap() in your driver.
>> You can also impliment poll() { select() } so your
>> application knows when new data are available.
>>
>> You cannot use a user-mode file-descriptor in the kernel.
>>
>
> Why not ?
http://kernelnewbies.org/FAQ/WhyWritingFilesFromKernelIsBad
>
> I'm suprised because what I need doens't seem so uncommon, usually
> devices send or
> receive data to/from files. So a helper (system call ?) to achieve
> that other than the basic
> read/write seems needed, no ?
Usually devices send or receive just data, and they shouldn't care about
file format, filesystems, permissions and all this stuff...
Regards,
Arnd
next prev parent reply other threads:[~2008-05-15 11:50 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-14 19:54 How to avoid data copies in a driver ? Francis Moreau
2008-05-14 20:02 ` Lennart Sorensen
2008-05-15 7:44 ` Francis Moreau
2008-05-15 13:59 ` Lennart Sorensen
2008-05-16 20:17 ` Francis Moreau
2008-05-14 21:23 ` linux-os (Dick Johnson)
2008-05-15 7:40 ` Francis Moreau
2008-05-15 11:50 ` Arnd Hannemann [this message]
2008-05-15 12:08 ` Francis Moreau
2008-05-15 13:16 ` linux-os (Dick Johnson)
2008-05-16 8:10 ` Jeremy Fitzhardinge
2008-05-16 11:44 ` Francis Moreau
2008-05-21 10:41 ` Pavel Machek
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