i've asked about this on the kernel newbies list, but i want to ask it here in a slightly different, fedora-centric way. the short form: what is the precise sequence of kernel boot regarding the initramfs (both the internal and external possibilities)? the long form: i'm reading the docs and trying to understand the intricacies of the boot sequence regarding how the kernel deals with the initramfs. first, AIUI, every built kernel has an *internal* compressed cpio initramfs image although, by default, it's "empty." now, i opened up one of the internal cpio initramfs images that's generated when i do my own kernel build, and it contained; drwxr-xr-x 2 root root 0 Sep 7 16:14 /dev crw------- 1 root root 5, 1 Sep 7 16:14 /dev/console drwx------ 2 root root 0 Sep 7 16:14 /root so it's not truly "empty" but it's pretty close. anyway, onward. based on my reading, it appears that, when the (2.6) kernel starts to run, it allocates a tmpfs-based "rootfs" (always, without exception) and copies into it the contents of the internal initramfs image (again, without excepton). is this correct so far? once that's done, what happens if there's an executable "init" file in the rootfs? does the kernel simply pass control to that executable? if that's true, that means that there would be no way to process regular kernel command-line parameters so, despite what the documentation seems to suggest, i can't believe that's what's happening. on the other hand, let's say there's no "init" in that internal initramfs. then, AIUI, the kernel will check whether it's been passed a second initramfs image (that would be the one identified in /etc/grub.conf via the "initrd" directive). and in the case of fedora, that's the one created by running "mkinitrd" during the kernel installation process, which *does* have an "init" script which fires up "nash" and takes over, etc, etc. but, once again, even if that happens, at what point in all of that would a kernel boot-time parameter of, say, "root=" be processed? surely *something* has to deal with that but in all of the above, where is that being done? and do i have the order even remotely correct? yes, i'm RTFS. but a quick clarification never hurts. thanks. rday p.s. once i figure it out, i'll be happy to summarize. -- ======================================================================== Robert P. J. Day Linux Consulting, Training and Annoying Kernel Pedantry Waterloo, Ontario, CANADA http://crashcourse.ca ========================================================================
