X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=qemu%2Froms%2Fu-boot%2Fdoc%2FREADME.mips;fp=qemu%2Froms%2Fu-boot%2Fdoc%2FREADME.mips;h=b28f6285ccbc5ffb7eaece5e351da628d9420763;hb=e44e3482bdb4d0ebde2d8b41830ac2cdb07948fb;hp=0000000000000000000000000000000000000000;hpb=9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00;p=kvmfornfv.git diff --git a/qemu/roms/u-boot/doc/README.mips b/qemu/roms/u-boot/doc/README.mips new file mode 100644 index 000000000..b28f6285c --- /dev/null +++ b/qemu/roms/u-boot/doc/README.mips @@ -0,0 +1,54 @@ + +Notes for the MIPS architecture port of U-Boot + +Toolchains +---------- + + http://www.denx.de/wiki/DULG/ELDK + ELDK < DULG < DENX + + http://www.emdebian.org/crosstools.html + Embedded Debian -- Cross-development toolchains + + http://buildroot.uclibc.org/ + Buildroot + +Known Issues +------------ + + * Cache incoherency issue caused by do_bootelf_exec() at cmd_elf.c + + Cache will be disabled before entering the loaded ELF image without + writing back and invalidating cache lines. This leads to cache + incoherency in most cases, unless the code gets loaded after U-Boot + re-initializes the cache. The more common uImage 'bootm' command does + not suffer this problem. + + [workaround] To avoid this cache incoherency, + 1) insert flush_cache(all) before calling dcache_disable(), or + 2) fix dcache_disable() to do both flushing and disabling cache. + + * Note that Linux users need to kill dcache_disable() in do_bootelf_exec() + or override do_bootelf_exec() not to disable I-/D-caches, because most + Linux/MIPS ports don't re-enable caches after entering kernel_entry. + +TODOs +----- + + * Probe CPU types, I-/D-cache and TLB size etc. automatically + + * Secondary cache support missing + + * Initialize TLB entries redardless of their use + + * R2000/R3000 class parts are not supported + + * Limited testing across different MIPS variants + + * Due to cache initialization issues, the DRAM on board must be + initialized in board specific assembler language before the cache init + code is run -- that is, initialize the DRAM in lowlevel_init(). + + * centralize/share more CPU code of MIPS32, MIPS64 and XBurst + + * support Qemu Malta