On Tue, Aug 16, 2016 at 05:36:07PM +0200, Ralf Baechle wrote: > On Tue, Aug 09, 2016 at 01:21:47PM +0100, James Hogan wrote: > > > Here are a couple of tweaks for MIPS memory setup, primarily in order to > > handle memory which extends right up to the end of physical memory on > > 32-bit systems with 32-bit phys_addr_t. More specifically we omit the > > final page of physical memory to avoid the overflow (see patch 1 for > > details). > > > > Patch 2 improves the rounding in the MAAR setup, so as to include the > > first full page of an already aligned region, and to avoid a BUG_ON for > > regions with non 64-KByte aligned end addresses (which I happened to hit > > while working on a different version of patch 1 which wasn't correctly > > merging the kernel data section into the main RAM region). > > There's a DMA issue with one of the system controllers on Malta which > afair only affects one endianess and can be worked around by not using > the last bit of memory. That isn't the only platform having such issues > I've seen and debugging has always been very painful so I'm wondering > if as a general precaution we should just leave the last page of memory > unused. If I understand you right, I think thats pretty much what patch 1 does, or rather it allows such a region to be created but reduces the length so it doesn't quite reach the end, I suppose assuming it will get rounded down to a page boundary. Cheers James
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