Subject: Re: allocmem in interrupt context
To: Iain Hibbert <>
From: Matthew Orgass <>
List: tech-kern
Date: 10/29/2005 15:59:10
On 2005-10-28 wrote:

> and none of those approaches splvm() so memory allocations should be ok, hm?

  No, memory allocation might sleep, so it needs a process context.

> It may be (certainly is, in fact) that I am unclear on the way the USB
> code works, documentation is minimal it seems..  not sure why the memory
> is being allocated in there in any case, as I am providing a buffer though
> it is not an usbd_alloc_buffer() buffer, was getting the transfer into an
> MBUF (cluster) data area so I can just pass it off directly.

  The buffer needs to be used for DMA, so it needs to come from bus_dma
allocation.  Unless you have a usbd_alloc_buffer buffer it will allocate a
new one.

Matthew Orgass