Re: [gentoo-user] Booting Gentoo from USB stick

[J. Roeleveld]

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