Subject: Re: physically contiguous memory
To: None <>
From: Marcus Comstedt <>
List: tech-kern
Date: 03/26/2001 15:10:02
>>>>> "Lennart" == Lennart Augustsson <> writes:

  Lennart> Looking at your description above it sounds like you want the PCI board
  Lennart> to be able to do DMA on the memory, so being contiguous is not the
  Lennart> only requirement you have. For instance, you also need to find the
  Lennart> "physical address" of the memory, and it has to be in an area that is
  Lennart> DMAable.  So bus_dma(9) looks like the right thing to me.
  Lennart>  uvm_pglistalloc() looks like it's on the totally wrong abstraction level.
  Lennart> It's messing with memory at a far too low level.

Yes, for allocating memory for a DMA buffer for a PCI card, the
bus_dma functions of the PCI busspace should definitely be used.  As
you say, this is _not_ the same thing as just allocating some
contiguous memory.

It's always so much easier when people actually explain what they are
trying to solve...   :-9

  // Marcus