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From: John Baldwin <jhb@freebsd.org>
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Date: Fri, 13 Feb 2009 09:57:10 -0500
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Cc: Patrick =?iso-8859-1?q?Lamaizi=E8re?= <patfbsd@davenulle.org>
Subject: Re: bus_dmamem_alloc() and BUS_DMA_WAITOK
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On Friday 13 February 2009 9:22:05 am Patrick Lamaizi=E8re wrote:
> Hello,
>=20
> I would like to know if it is safe to use the BUS_DMA_WAITOK flag with
> bus_dmamem_alloc(), in the context of the device_attach routine? Many
> drivers use BUS_DMA_NOWAIT.

Yes, it is ok to use in an attach routine.

> I need a 32Ko buffer and on low memory my driver cannot attach
> (bus_dmamem_alloc returns ENOMEM). Will BUS_DMA_WAITOK help in this
> case?

I'm not sure if it will really help, though.  You might end up blocking=20
forever (or a long time) until a 32k region is freed.

=2D-=20
John Baldwin