Messages in this thread | | | Date | Thu, 15 May 2008 14:08:39 +0200 | From | "Francis Moreau" <> | Subject | Re: How to avoid data copies in a driver ? |
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On Thu, May 15, 2008 at 1:50 PM, Arnd Hannemann <arnd@arndnet.de> wrote: > 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 >
ok, relayfs might be what I need, thanks.
>> >> 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... >
The fact is that the data usually ends into a file.
thanks -- Francis
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