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Date: Thu, 14 Sep 2006 11:47:01 +0200
From: Jan Kiszka <jan.kiszka@domain.hid>
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Subject: Re: [Xenomai-help] IPC
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To: Nilanjan Roychowdhury <Nilanjan.Roychowdhury@domain.hid>
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Nilanjan Roychowdhury wrote:
> Hi
>=20
> What is the best IPC ( in terms of performance) between any user space
> XENOMAI task and a user space Linux thread ?
>=20
> I know pipes can be used between kernel space XENOMAI task and user
> space Linux thread ?

For larger blocks: shared memory.

We added the rtdm_mmap_to_user service for this purpose.
You can build up an interface on to of it (some IOCTL to establish a
memory region with a user process, some furthers to inform the user
about a valid data block and to signal the driver about the end of
processing that block). This even allows to export DMA memory directly
to the user, i.e. providing zero-copy. Already successfully applied on
an (unpublished) framegrabbing driver.

Jan


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