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====== Booting Ubuntu with BKO ====== ===== Locating from where does the nfsboot is getting called ===== ==== Mistory of do_nfsmount ==== //do_nfsmount// is defined at two places, why?\\ - ///scripts/casper +198// - ///scripts/nfs +8// My guess is that file ///scripts/nfs// is not used, it is just present there from older versions and has not been removed.\\ //do_nfsmount// function is getting called from ///scripts/casper +188// which is from inside of <code>do_netmount()</code> and depend on variable <code>${NETBOOT}</code> The //do_netmount()// is getting called from //mountroot()// which is inside ///scripts/casper +581// and the call depends on variable presense of variable //${NETBOOT}// which is the boot parameter value of parameter //netboot// ===== qemu + ubuntu 9.04 Desktop i386 booting problem ===== ubuntu-9.04-desktop-i386.iso is refusing to boot over qemu. I am using command line <code> qemu -cdrom /var/www/ubuntu-9.04-desktop-i386.iso -net nic -net user </code> It gives error gives error : <code> [ 3.284007] ..MP-BIOS bug: 8254 timer not connected to IO-APIC </code> and freezes.\\ I am using following version of qemu <code> $ qemu QEMU PC emulator version 0.10.0, Copyright (c) 2003-2008 Fabrice Bellard </code> The BIOS number was found and BIOS version used by qemu is as follows <code> QEMU BIOS - build: 08/15/08 $Revision: 1.209 $date: 2008/06/02 20:08:10$ </code> I had to update my qemu to version 0.10.5 then it started working <code> $ qemu QEMU PC emulator version 0.10.5, Copyright (c) 2003-2008 Fabrice Bellard </code> ===== SQUASHFS error ===== I am getting following errors in the process of booting. My guess is, most of these errors are related to failure of httpfs in providing requested logical block, but I need to confirm this. <code> Buffer I/O error on device loop0, logical block 272374 SQUASHFS error: sb_bread is failed reading block 0x845d5 SQUASHFS error: unable to read fragment cache block [211696cb] SQUASHFS error: unable to read page, block 211696cb, size c115 </code> I have seen this error before, but if I retry the booting then it works. But now, I have failed two consecutive time on local webserver, which is quite alarming. ====== Ubuntu revisited (in way of debian) ====== I was preparing to write an email to ubuntu mailing list, here is what I assembled for that email <code> I have tried booting Knoppix and debian over HTTP, and they work fine. But I have problem in booting Ubuntu (ubuntu-9.04-desktop-i386.iso) over HTTP. The procedure followed to boot linux over HTTPFS by me is as follows. I get hold of ISO of live CD, and get the kernel, initramfs and filesystem.squashfs from it. I host ISO of live CD and "filesystem.squashfs" on webserver. I modify initramfs to include httpfs and related tools and modules. I modify "/init" ( "/scripts/casper" in case of ubuntu ) to use httpfs for mounting. I pass boot parameter "httpfs=http://ip-of-webserver/filesystem.squashfs" or "httpfs=http://ip-of-webserver/ubuntu-9.04-desktop-i386.iso" I have attempted booting with both livecd.iso and filesystem.squashfs. In both cases, I get different errors. I know that filesystem is getting mounted with HTTPFS. I have verified it from the rescue shell. I get this rescue shell by executing wrong command in initramfs. When I mount "ubuntu-9.04-desktop-i386.iso" I get following error {{{ Buffer I/O error on device loop0, logical block 272374 SQUASHFS error: sb_bread is failed reading block 0x845d5 SQUASHFS error: unable to read fragment cache block [211696cb] SQUASHFS error: unable to read page, block 211696cb, size c115 }}} Then I tried to use debian way of mounting "filesystem.squashfs" for booting. I get error {{{ Begin: Running /scripts/init-bottom ... Done. run-init: nuking initramfs contents: Directory not empty Kernel panic - not syncing: Attempted to kill init! Dumping ftrace buffer: (ftrace buffer empty) }}} My guess is that, this error is triggered because when "/bin/run-init" tries to remove initramfs and fails to remove some file. Most probably it can be /dev/loop0 as it is in use by loopback mount command. I checked debian code, the use of loopback is avoided there. So, I am doing the same for ubuntu now. I wont use loopback and see if it works. I was wondering what I am doing wrong as the same method works fine with debian. And when I try to mount ISO itself, I get kernel panic </code> Got some information about this error on [[http://wiki.debian.org/initramfs/More|debian wiki]] which says that <code> When switching another root device, initrd would pivot_root and then umount the ramdisk. But initramfs is rootfs: you shouldn't pivot_root rootfs and can't unmount it. Just delete everything out of it (except the new block device node, if any), overmount /, and exec the new init. (The klibc package contains a helper program in utils/run_init.c to do this for you, and other packages have adopted this as switch_root.) </code> Now, I don't know for sure, which files are not getting deleated and hence causing problem. ==== A question ==== what is the differnece between debian script and ubuntu script that filesystem.squashfs is not working with ubuntu, but it works with debian? - comparing ''d/scripts/live'' with ''u/scripts/casper'' --- too different, diff went crazy with this command. They are as good as seperate program who do similar work. - comparing ''d/bin/run-init'' with ''u/bin/run-init'', --- they are same. - comparing ''d/init'' with ''u/init'' -- not much of difference This approach is not working for me, I will try another approach. ==== analyzing run_init.c ==== My guess is that, run_init.c is the one who is dying, and it seems he does allow you to specify the files which should not be deleted. I want to see how to tell that to run_init.c - Another thing that I want to try out is, what if I dont delete the contents of initramfs? I will remove that check from run_init.c will system still boot? - My guess is that, ''overmount /'' may fail. - Now, I need to locate the source code of run_init.c ===== Ubuntu over iscsi ===== - Following the line of [[BKODebianISCSI|Debian over iscsi]], attempted the Ubuntu over iscsi, but it did not worked. ===== Problem found ===== - From the progress in fedora, it seems that problem is because network is restarting itself, which kills the the network and mounted HTTPFS. Culprits are - ''/etc/init.d/network'' - ''/etc/init.d/NetworkManager''
