Messages in this thread | | | From | Li Yang-r58472 <> | Subject | RE: [PATCH] powerpc:Fix rheap alignment problem | Date | Mon, 3 Jul 2006 20:19:05 +0800 |
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> > > Two problems with genalloc that I can see (for CPM programming): > > > 1) (minor) Does not have a way to specify alignment (genalloc does it for > you) > > > 2) (major problerm, at least for me) Does not have a way to allocate a > specified address in the pool. > > > > > > 2 is needed esp when programming MCC drivers, since a lot of the > datastructures must be in DP RAM _and_ be in a specific spot. And if you cannot > tell the allocator that I am using a specific address, then the allocator might > very well give somebody else that portion of RAM. The only solution without > a fixed allocator is to allocate ALL memory in the DP RAM and use your own > allocator. > > > > > > > Yeah, that too. > > > > Too bad there are no main tree drivers like that, but they do exist. > > > > One could conceivably hack genalloc to do that, but will end up with > > something complex too. > > > > BTW, there are other uEngine based architectures with similar alignment > > requirements. > > > > So in conclusion, for the in-tree drivers genalloc is sufficient as an cpm > memory allocator. > > For some out of tree drivers, it is not. > > Sounds like a good enough justification to keep rheap for now then.
As the reason I stated in the last mail, rheap should continue being used not only for this fix-address situation but also for CPM/QE buffer descriptor management. Rheap and genalloc are two different implementations of dynamic memory allocator, which have different suitable cases. Both of them should be kept for different applications. > > Ben.
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