[PATCH v2] powerpc: align DTL buffer to AMS boundary

Michael Ellerman michael at ellerman.id.au
Thu Apr 14 14:12:43 EST 2011

On Wed, 2011-04-13 at 15:33 -0700, Nishanth Aravamudan wrote:
> PAPR specifies that DTL buffers can not cross AMS environments (aka CMO
> in the PAPR) and can not cross a memory entitlement granule boundary
> (4k). This is found in section H_REGISTER_VPA of the PAPR.
> kmalloc does not guarantee an alignment of the allocation, though,
> beyond 8 bytes (at least in my understanding). Over-allocate and align
> the resulting address.

You can specify alignment by creating your own kmem_cache, ie.

Obviously there will be some overhead to create the cache structure, but
I'd think it will be less than 4k * NR_CPUs.


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