On Tue, 2009-02-24 at 09:00 +0100, Seewer Philippe wrote: > Hi all > > Warren Togami wrote: > [snip] > > root=dhcp is a kernel cmdline given by the bootloader (syslinux, grub, > > pxelinux, etc.) which directs the initrd during runtime to bring up eth0 > > and do DHCP. It then mounts the rootfs depending on options given by > > the DHCP server. Fedora 10 mkinitrd implements the following two types > > of mounts with root=dhcp. > > > > option root-path "172.31.100.254:/path/to/target_root"; > > option root-path "nbd:172.31.100.254:2000:squashfs:ro"; > > > > An existing RFC specifies syntax for iscsi that could be implemented as > > well. (Although iscsi is problematic because some types require > > authentication.) Arbitrary types of root=dhcp rootfs mounts can be > > implemented with hooks made possible with your patch. > > A question: Why not use root=/dev/nfs and the other options according to > kernel doc, like nfsroot=... and ip=autoconf? For me that is much more > readable. It is a matter of taste and historical contingency, I suppose. The current nfsroot mounting stuff was added way before initramfs/initrd was an option, and it was probably easier to not mess up the in-kernel root= handling code (which expected a device to mount). Since initramfs handles all that stuff now (assuming you are using it, of course), the kernel neither knows nor cares about the contents of the root= parameter, and we do not have to be bound by its restrictions. We can make (for example) root=192.168.10.2:/my/root/path do The Right Thing and mount that as an nfs filesystem. We would still handle the other case, of course. > Maybe even leave nfsroot-mounting to the kernel as long as that features > remains in the tree. That is impossible when using an initramfs. Once the kernel notices an initramfs, finds /init on it and execs it, it is up to the initramfs to handle everything else. > I guess nbd and iscsi could go the same way like root=/dev/iscsi ... It is as easy to handle it one way or the other in userspace. I happen to think that overloading root= is easier to read, and prevents having to remember yet another *root parameter when someone invents an even more convoluted and crazy way to store a filesystem. :) > Regards, > Philippe > -- > To unsubscribe from this list: send the line "unsubscribe initramfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Victor Lowther RHCE# 805008539634727 LPIC-2# LPI000140019 -- To unsubscribe from this list: send the line "unsubscribe initramfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
