Hello, * Mathias Kresin (d...@kresin.me) wrote: > I'm in doubt that the lzma splitter can be fixed. > > The dependency to align the rootfs isn't specific to the lzma > splitter. mtd_find_rootfs_from() in mtdsplit.c uses the erase block > size as step size. > > For the other splitter an not erase block size aligned rootfs works > only because the headers provide informations about the kernel size > and we can pass the kernel size as offset to mtd_find_rootfs_from() > to prevent stepping over the mtd. > > But the lzma header doesn't provide any informations about > kernel/compressed size. Only the uncompressed size is stored in the > header. According to the LZMA SDK, the LZMA decoder simply stops > decompressing as soon as the amount of decompressed data matches the > value stored in the header. > > The only fix I can think of, would be to change the step size in > mtd_find_rootfs_from() to 1 byte. But that would introduce a huge > performance penalty.
I tried the naive approach, except stepping every 4 bytes given John's remarks. It does incur some performance penalty, slowing boot down about 0.6 seconds. before; aligned to eraseblock [ 0.667565] 0x000000040000-0x000000400000 : "firmware" [ 0.684885] 2 lzma-fw partitions found on MTD device firmware [ 0.696634] 0x000000040000-0x000000180000 : "kernel" [ 0.711025] 0x000000180000-0x000000400000 : "rootfs" after; aligned to 4 bytes only [ 0.667375] 0x000000040000-0x000000400000 : "firmware" [ 1.293574] 2 lzma-fw partitions found on MTD device firmware [ 1.305285] 0x000000040000-0x000000170ad4 : "kernel" [ 1.319547] 0x000000170ad4-0x000000400000 : "rootfs" At least in the case of this board it's not a huge delay. But given that the search happens in mtd_find_rootfs_from() and affects other models, the impact is likely to be more severe elsewhere. Either approach fixes the oddball AR670W, which currently does not boot LEDE. It uses u-boot, but the developers hardcoded an "uImage" so that there's no length parameter to search from. I suppose it's nice to have the extra 64k in rootfs_data with the second approach. -Claudio _______________________________________________ Lede-dev mailing list Lede-dev@lists.infradead.org http://lists.infradead.org/mailman/listinfo/lede-dev
