Re: [PATCH] generic device DMA (dma_pool update)

James Bottomley
2003-01-01T19:39:50Z

adam@yggdrasil.com said:
> I thought Andrew Morton's request for a gfp flag was for allocating
> memory from a pool (for example, a "read ahead" will want to abort if
> memory is unavailable rather than wait).

Well, yes, but the underlying allocators will also have to take the flag too
so that all the semantics are correct.

adam@yggdrasil.com said:
> Can someone show me or invent an example of two different uses of
> dma_alloc_coherent that really should use different policies on
> whether to block or not?

The obvious one is allocations from interrupt routines, which must be
GFP_ATOMIC (ignoring the issue of whether a driver should be doing a memory
allocation in an interrupt). Allocating large pools at driver initialisation
should probably be GFP_KERNEL as you say.

James