On 08/25/2014 20:36, David Daney wrote: > On 08/25/2014 04:55 PM, Joshua Kinard wrote: >> On 08/25/2014 13:16, Ralf Baechle wrote: >>> On Sat, Aug 02, 2014 at 05:11:37AM +0400, Max Filippov wrote: >>> >>>> this series adds mapping color control to the generic kmap code, allowing >>>> architectures with aliasing VIPT cache to use high memory. There's also >>>> use example of this new interface by xtensa. >>> >>> I haven't actually ported this to MIPS but it certainly appears to be >>> the right framework to get highmem aliases handled on MIPS, too. >>> >>> Though I still consider increasing PAGE_SIZE to 16k the preferable >>> solution because it will entirly do away with cache aliases. >> >> Won't setting PAGE_SIZE to 16k break some existing userlands (o32)? I use a >> 4k PAGE_SIZE because the last few times I've tried 16k or 64k, init won't >> load (SIGSEGVs or such, which panicks the kernel). >> > > It isn't supposed to break things. Using "stock" toolchains should result > in executables that will run with any page size. > > In the past, some geniuses came up with some linker (ld) patches that, in > order to save a few KB of RAM, produced executables that ran only on 4K pages. > > There were some equally astute Debian emacs package maintainers that were > carrying emacs patches into Debian that would not work on non-4K page size > systems. > > That said, I think such thinking should be punished. The punishment should > be to not have their software run when we select non-4K page sizes. The > vast majority of prepackaged software runs just fine with a larger page size. Well, it does appear to mostly work now w/ 16k PAGE_SIZE. The Octane booted into userland with just a couple of "illegal instruction" errors from 'rm' and 'mdadm'. I wonder if that's tied to a hardcoded PAGE_SIZE somewhere. Have to dig around and find something that reproduces the problem on demand. -- Joshua Kinard Gentoo/MIPS kumba@xxxxxxxxxx 4096R/D25D95E3 2011-03-28 "The past tempts us, the present confuses us, the future frightens us. And our lives slip away, moment by moment, lost in that vast, terrible in-between." --Emperor Turhan, Centauri Republic
