[OpenWrt-Devel] Unable to mount squashfs, no real error returned (Invalid argument)
Hey, I have original firmware installed on my (unsupported) router and I'm booting ELF image using tftp. My purpose is to get correct partitions layout and access to them. Linux correctly detects mtds, I get: 0x001c-0x001416a4 : linux 0x001416a4-0x007ba000 : rootfs # cat /proc/mtd dev:size erasesize name mtd0: 001e boot mtd1: 0001 board_data mtd2: 0001 nvram mtd3: 00141688 0002 linux mtd4: 0067895c 0002 rootfs So the mtd I'm interested in is mtd4. # head /dev/mtd4 | hexdump -C 73 68 73 71 2b 03 00 00 00 00 00 54 03 00 00 d8 |shsq+..T| # head /dev/mtdblock4 | hexdump -C head: /: Input/output error 3d 3d 3e 20 2f 20 3c 3d 3d 0a 0a 3d 3d 3e 20 64 |== / ==..== d| 0010 65 76 2f 6d 74 64 62 6c 6f 63 6b 34 20 3c 3d 3d |ev/mtdblock4 ==| 0020 0a 73 68 73 71 2b 03 00 00 00 00 00 54 03 00 00 |.shsq+..T...| Again... # head /dev/mtdblock4 | hexdump -C 73 68 73 71 2b 03 00 00 00 00 00 54 03 00 00 d8 |shsq+..T| Now the most interesting part: # mount -t squashfs /dev/mtdblock4 /mnt/ mount: mounting /dev/mtdblock4 on /mnt/ failed: Invalid argument Can someone explain to me, what does it mean? Is there something wrong with my mtdblock4? I don't get anything interesting in dmesg. Is that possible squashfs used by original firmware is somehow malformed and requires original-vendor-hacked squashfs support? -- Rafał ___ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/mailman/listinfo/openwrt-devel
Re: [OpenWrt-Devel] Unable to mount squashfs, no real error returned (Invalid argument)
Hi Rafał, On 24 August 2012 23:09, Rafał Miłecki zaj...@gmail.com wrote: (...) # head /dev/mtd4 | hexdump -C 73 68 73 71 2b 03 00 00 00 00 00 54 03 00 00 d8 |shsq+..T| (...) Can someone explain to me, what does it mean? Is there something wrong with my mtdblock4? I don't get anything interesting in dmesg. The problem is that Broadcom uses its own squashfs with lzma-magic. The standard squashfs magic is sqsh or hsqs (depending on endianess), and Broadcom chose to use a different one (since squashfs3 does not support storing the compressor type). There is a patch adding support for unsquashfs in the repo (so you should be able to just throw a copy of the image at it), but the in-kernel squashfs only accepts standard squashfs magics. Jonas ___ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/mailman/listinfo/openwrt-devel
Re: [OpenWrt-Devel] Unable to mount squashfs, no real error returned (Invalid argument)
2012/8/24 Jonas Gorski jonas.gorski+open...@gmail.com: Hi Rafał, On 24 August 2012 23:09, Rafał Miłecki zaj...@gmail.com wrote: (...) # head /dev/mtd4 | hexdump -C 73 68 73 71 2b 03 00 00 00 00 00 54 03 00 00 d8 |shsq+..T| (...) Can someone explain to me, what does it mean? Is there something wrong with my mtdblock4? I don't get anything interesting in dmesg. The problem is that Broadcom uses its own squashfs with lzma-magic. The standard squashfs magic is sqsh or hsqs (depending on endianess), and Broadcom chose to use a different one (since squashfs3 does not support storing the compressor type). There is a patch adding support for unsquashfs in the repo (so you should be able to just throw a copy of the image at it), but the in-kernel squashfs only accepts standard squashfs magics. Ah, OK, thanks a lot! I've managed to track where mounting fails. It's fs/squashfs/super.c::squashfs_fill_super. As you said, it fails at: if (sb-s_magic != SQUASHFS_MAGIC) Unfortunately error wasn't displayed to me, because flag MS_SILENT was set. Backtrace after I put WARN_ON(1): [ 33.984000] [ cut here ] [ 33.988000] WARNING: at fs/squashfs/super.c:126 squashfs_fill_super+0x1a0/0x84c() [ 33.996000] Modules linked in: [ 34.00] Call Trace: [ 34.004000] [8025ce80] dump_stack+0x8/0x34 [ 34.008000] [80023780] warn_slowpath_common+0x78/0xa4 [ 34.012000] [800237c4] warn_slowpath_null+0x18/0x24 [ 34.016000] [80103640] squashfs_fill_super+0x1a0/0x84c [ 34.024000] [800a7c0c] mount_bdev+0x14c/0x1cc [ 34.028000] [801033b0] squashfs_mount+0x18/0x24 [ 34.032000] [800a856c] mount_fs+0x20/0xe4 [ 34.036000] [800bfaf4] vfs_kern_mount+0x64/0xe8 [ 34.04] [800bfda0] do_kern_mount+0x48/0xf4 [ 34.048000] [800c1cc0] do_mount+0x67c/0x6fc [ 34.052000] [800c1dcc] sys_mount+0x8c/0xf0 [ 34.056000] [8000d1d0] stack_done+0x20/0x40 [ 34.06] [ 34.06] ---[ end trace 088bd3492332a7b0 ]--- -- Rafał ___ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/mailman/listinfo/openwrt-devel
