# Booting from external USB drive with kernel 2.6.1x [Solved]

## Triptol

I have a big (120Gb) external USB 2.0 drive which I use to boot my office laptop at home. My company only uses stuff from Redmond and they don't allow anything else on the laptop. The external harddisk ensures my fun during the weekends.

Now the thing is that life was nice and good up until 2.6.10 came along. The release notes stated something like a lot of enhancements USB boot users would like. Yeah right: unable to mount root device. No more booting, I'm really pleased. The kernel already tries to boot from /dev/sda3 before the built-in usb-storage driver actually has done its work.

So here I am still using 2.6.9. I have come up with the following:

- there seems to be a patch for 2.2 and 2.4 which basically mounts a couple of times and when not succesful waits for a second- a lot of people suggest using a special initrd with the usb-storage and sd_mod preloaded (information can be found here). This does not work for me. Ideally I'm looking for something I know from the Adaptec SCSI drivers: an official delay time you can enter in the kernel config. Now since that probably is not around I would like to know from people who can get it to work. I'm not too happy applying a 2.2 or 2.4 patch to my 2.6 kernel, but if that is what it takes...

To be more clear: everything worked with kernel 2.6.7, 2.6.8 and 2.6.9. The release of 2.6.10 was where the problems started. The problems are not yet resolved in 2.6.12. And I'm using almost the same config for all kerneles (make oldconfig does some changes though).Last edited by Triptol on Mon Jun 20, 2005 8:56 pm; edited 1 time in total

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## thomasmue

Hi,

i've done the same with an 80GB external USB 2.0 drive. Found some threads here and there. I also built that initrd, but it comes down to generate enough delay for allowing the usb subsystem to finish. My setup needs 8 seconds, so  I have a 10 second delay. Worked with the 2.6.11 kernels.

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## Triptol

Could you explain how you've created the delay? I have not been able to identify anything but this patch for 2.2 and 2.4. Are you suggesting I should use that? Or did you (hopefully) do somthing else to set the delay?

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## dsd

i contributed a patch for this issue which was accepted into 2.6.11

boot with kernel parameter "rootdelay=5" for a 5 second delay before mounting root

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## Triptol

Thanks. This was the answer I was hoping for, will be checking it out in a second. Very cool.  :Very Happy: 

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## Triptol

Works like a charm!!!

Man this is so great, been waiting for it since 2.6.10... And it has been there since 2.6.11. Why isn't this readily available on the net... Nevermind. Fixed it. Thanks.

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## dsd

it has been discussed a few times in various places and is also documented at Documentation/kernel-parameters.txt

theres not much more you can do for such a small feature

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## Triptol

I've done some forum searches and couldn't find anything useful (could be my problem). I've also done some google searches and found a lot of people with the same problem, but no answers... That's why I was amazed. 

Is this a Gentoo specific patch or has it been accepted by the kernel development team (it should be)?

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## dsd

it is in mainline

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## liljohn118th

 *dsd wrote:*   

> it has been discussed a few times in various places and is also documented at Documentation/kernel-parameters.txt
> 
> theres not much more you can do for such a small feature

 

I just found this thread after a few days of bashing my head against the wall (and doing a lot of searching here on the forums). It seems like they could mention this in the install handbook during grub configuration.  They mention a couple of the extra parameters you can pass at boot time using grub (such as vga), it seems to me like this might warrant a sentance, too... just a random thought. Anyway, thanks for getting this in, it's a lifesaver!

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