Peter and Sam CC'ed [Michael Tokarev - Fri, Oct 09, 2009 at 06:17:50PM +0400] > Ok, finally the mystery solved. After a week of > digging. > > The original problem was titled "Cannot boot on > a PIII Celeron", and Rafael filed a bug #14270 > for this. > > In short, what I observed was that a new kernel > (2.6.31) fails to boot on a PIII Celeron machine. > But changing just the CPU to plain PIII and voila, > it now works. I don't know why it behaved this > way, but I found where was the problem, finally. > > And the problem is in the last stage of build, when > building the bzImage. > > make -f scripts/Makefile.build obj=arch/x86/boot/compressed arch/x86/boot/compressed/vmlinux > ... > (cat arch/x86/boot/compressed/vmlinux.bin | lzma -9 && echo -ne \\x38\\xd6\\x37\\x00) > arch/x86/boot/compressed/vmlinux.bin.lzma > ... > > Note the echo command. > > Now, Debian switched to dash as /bin/sh. And dash > does not understand the -e option: > > $ dash -c 'echo -ne \\x38\\xd6\\x37\\x00' | od -x > 0000000 6e2d 2065 785c 3833 785c 3664 785c 3733 > 0000020 785c 3030 000a > > $ bash -c 'echo -ne \\x38\\xd6\\x37\\x00' | od -x > 0000000 d638 0037 > > So the final size (it's the size of uncompressed file) > becomes incorrect. Here's what mkpiggy outputs for > this (in arch/x86/boot/compressed/piggy.S): > > z_output_len = 170930296 > > while it should be > > z_output_len = 3659320 > > And with the former (wrong, larger) size, the whole > thing just reboots on a PIII Celeron. I've no idea > why, but the original problem is here. > > The same thing happens with bzip2 algorithm which is > not new, not only with lzma. > > The whole thing looks quite hackish to me, -- mkpiggy > can know the size from the original image just fine, > instead of getting it from the end of already compressed > file. > > For now, quick fix is to change echo to printf in there. > Correct fix is to re-write mkpiggy to look at the > original file for size (IMHO anyway). > > And this is a very good candidate for -stable as well. > The bug is very difficult to find. And now when more > and more people who use Debian are switching to dash, > it will be more common. > > Thanks! > > /mjt > -- Cyrill -- To unsubscribe from this list: send the line "unsubscribe kernel-testers" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
