On Wed, 2009-10-07 at 14:06 +0800, vichy wrote:
> Dear all:
> I try to pass the content of file,1G, to kernel driver for operation
How? With which sys-calls?
> and then return the result back to application.
> My questions are:
> 1. The only way I can use is copy_from_user? If so, does it have the
> size limitation?
Not really. Even if, you can call it several times (for different parts
of the data) anyways.
> 2. I don't want my application pending on the I/O and is there any
> smart way to let the application know when driver finishes its job?
> appreciate your help,
Depends on the sys-calls:
- you could use read(2) and write(2): Which has the feature that
the user-space app could write chunks of it and the kernel driver
can process that immediately (e.g. for compressing the data or
similar).
The user-space app would block on the read(2) for the result.
- you could use an ioctl() which blocks and returns after the driver is
done (and you can/should use the same buffer for passing data and
receiving it).
- you could use two ioctl()s - one for passing data to the kernel,
another for blocking and getting it back.
Additionally (and indepently) you can send SIGIO (or some other signal?)
to the process^Wfile-descriptor to inform the process(es)that the driver
is done.
Bernd
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Firmix Software GmbH http://www.firmix.at/
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