On 21/09/10 17:26, J. Roeleveld wrote: > On Tuesday 21 September 2010 07:35:13 Jake Moe wrote: >> On 16/09/10 21:30, J. Roeleveld wrote: > <snipped old stuff> > >>> Please bear in mind, I have not actually used nor needed a ramdisk to >>> boot from ever since I started using Gentoo. >>> Not even when I played with booting from USB-sticks myself. >>> I simply build the kernel with all the necessary drivers compiled-in and >>> used that to boot from. >>> >>> This might also be an idea for you? >>> >>> -- >>> Joost >>> >>> Eg. if you do the mknod-commands to build the /dev/sda, /dev/sda1,.... >>> device nodes, then it should be able to continue. >> Well, I've finally gotten this to work with a manually config'ed >> kernel. Before, I was only getting kernel panics. Now, after your >> comment "all compiled-in", I took the old config I tried, did a sed to >> change all "=m" to "=y", and recompiled, and it worked. So obviously, >> there was some option that I wasn't building into the kernel (only as a >> module) that was needed to start from USB. > That's generally a good way to start, stick everything in the kernel :) > >> I had previously started from a working config I had previously used for >> the same model PC that I was doing my testing on, and just changed the >> USB drivers from modules to built-in, but apparently that's not enough. >> Any ideas what else is needed for a USB-stick boot that's not needed in >> a SATA boot? I'd like to a) find out what I missed, and b) be able to >> cull the kernel back down again, so I can build up lots of SATA, >> graphics and audio modules to make this able to boot (and work properly) >> on other systems. > Ok, doing this from memory here. > To be able to boot from USB, you need (additionally to what you normally > have): > 1) USB Host drivers (OHCI,UHCI,EHCI,...) > 2) USB Mass Storage > 3) file system on the USB-stick > 4) SCSI-disk (USB Mass storage depends on this) > > If others can also have a quick look on this list to check that I didn't miss > anything? > > -- > Joost > Well, now that I've managed to get it booting, the only problem is that I can't seem to get the disk label working right. In GRUB's menu.lst, if I use root=LABEL=UsbRoot, it doesn't work (kernel panic, label not found, but sda1 is listed as available), but if I use root=/dev/sda1, it works. However, later in the boot process, it mounts / using LABEL=UsbRoot in fstab just fine. Is that a problem with GRUB? Or the kernel? Or am I doing something else wrong?
And for future reference, while looking into various things for this, I found these in the Gentoo Wiki: USB Portable Install - http://en.gentoo-wiki.com/wiki/USB_Portable_Install Portable USB Gentoo - http://en.gentoo-wiki.com/wiki/Portable_USB_Gentoo Unfortunately, both use genkernel instead of manually configured kernels, so that part doesn't help, but one mentions the option "scandelay=2" to add to the kernel boot line in GRUB to introduce the delay genkernel needed to see the USB device; would have been good to know that last week when I was trying genkernel. :-P Jake Moe
