On Wed, 23 Oct 2002, Dinesh Nagpure wrote: > I am almost done with my porting of kernel 2.4.16 to our platform using > RM5231A. But I had to make a couple of very basic hacks and I am trying to > understand if there is any way I can avoid them. The kernel is almost a year old -- there were numerous fixes since then. Consider grabbing a recent (currently 2.4.20-pre6) version from the CVS. What I'm writing below refers to the current 2.4.x kernel. > First the memcpy wouldn't work for me properly, both the compiler generated > and also the one under arch/mips/lib/memcpy.c, so I had to change the lib > version to do byte copy. I know this is a very crude change but things > worked. You mean arch/mips/lib/memcpy.S, don't you? There were problems detected and fixed there this year. > Second, the Kseg0 coherency algorithm selection in the function > ld_mmu_r4xx0( ) seems to be improper for RM5231A, This function sets the CP0 > config register K0 field to 3 which as per RM5231A user manual is Cacheable, > noncoherent, write back policy Should this not be set to 0, which is > cacheable, non-coherent, write-through, no write allocate? See CONF_CM_DEFAULT in include/asm-mips/pgtable-bits.h for how to select the KSEG0 caching policy in ld_mmu_r4xx0(). If that is not appropriate, you probably need a separate function to do the initialization (e.g. ld_mmu_rm5231()) in a separate file (e.g. arch/mips/mm/c-rm5231.c). > Also from the knowledge base I understand there is a cache aliasing problem > associated with RM5231A when page size is set to 4KB. The document > recommends to invalidate the cache before retiring a virtual page OR > coloring of the pages. Can someone tell me if this fix is already taken care > of? For me when I enable caching under "Kernel hacking" my kernel crashes > with page fault, when it tries to run bin/init, consistently. I can't help here, but you definitely want to upgrade your kernel before going any further -- you may hit bugs that were fixed long ago and you may try handling problems someone else already resolved. -- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available +
