John Nilsson john at
Mon Nov 21 16:07:00 CST 2005

On Mon, 2005-11-21 at 22:35 +0100, Ante Karamatic wrote:
> On Mon, 2005-11-21 at 22:01 +0100, John Nilsson wrote:
> > Of course, but with information from the bootloader there is no need for
> > probe and autodetection.
> What information? You should read some documentation about bootloaders
> and master boot record. It's not autodetecion, it's support for USB.
> Nature of USB is that it scans for devices. It's not that Ubuntu does
> that, USB (as a hardware does that), same as SCSI controllers do. USB
> support in kernel isn't a thing that makes Ubuntu boot slow. Whole
> kernel takes 3-4 seconds. You should really leave kernel alone, since it
> is not weakest link in booting. Problem is in SysV.

Maybe I wasn't clear. The problem was that if people have to mount USB
disks the drivers must be loaded. And as I understood it the drivers for
USB is loaded by initramfs before letting init do it's thing. This takes
time (based on what mdz said earlier in the thread), even if you don't
need USB to mount root.

I simply meant that if you know that root is on an USB device this can
be (and probably is) reflected in the parameters to the kernel. If
"root=/dev/hd??" you can be pretty sure that you don't need USB to mount
root, thus no need to load USB drivers before giving up power to init.

So the whole point of my suggestion was not to not load USB at all. Just
defer it if possible to a later stage in the boot process so that it can
be loaded in parallel.


More information about the ubuntu-devel mailing list