# [SOLVED] CONFIG_SCSI_MULTI_LUN=y causes reboot after GRUB

## benny1967

I've been using my kernel config for quite a while now, applying changes only when absolutely necessary. Recently, I bought a phone that exposes both internal memory and SD-card as two USB mass storage devices. Using Windows (on this one PC I'm running Gentoo on), they both show up as I: and J:

Gentoo only showed one of the 2 drives; after some research I found that 

CONFIG_SCSI_MULTI_LUN

wasn't set in the kernel config although it needs to be in order to "see" both drives. OK, changes that, re-compiled, booted.. and for the first time in my life, I had a non-working kernel.  :Wink: 

What happens is that after I select the kernel version (2.6.31-gentoo-r6, btw) from the GRUB menu, the screen goes blank for a few seconds (no text, nothing I could interpret for debugging), then the whole box re-boots (=I see the BIOS messages coming up again) and I'm back to GRUB. Repeats forever.

I tried to play with max_scsi_luns=n as boot parameters (n being 1 or 2), which was another thing I read somewhere. Didn't help, system still re-boots.

So I went back to the old config with

# CONFIG_SCSI_MULTI_LUN is not set

and can't access the SD card in my phone. Bad.

Any suggestions on how to find the error here? It could be hardware related, couldn't it? But then... Windows seems to do just what I want, so there has to be a way to make it work on this hardware.

My GRUB-config reads:

title=Gentoo Linux Kernel 2.6.31-r6

root (hd0,0)

kernel /boot/kernel-2.6.31-gentoo-r6 root=/dev/sda2 video=uvesafb:1024x768-32,mtrr:3,ywrap splash=silent,theme:livecd-2007.0 CONSOLE=/dev/tty1 

initrd /boot/fbsplash-livecd-2007.0-1024x768

Any ideas on where to start? It's difficult if you don't get any output.  :Wink: Last edited by benny1967 on Wed Dec 30, 2009 1:05 pm; edited 1 time in total

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## gringo

really weird, isn´t it ? 

i suppose this does not only happens with the phone connected and are you really sure that the only difference is the CONFIG_SCSI_MULTI_LUN option in the kernel config ? 

The help text doesn´t really say anythig relevant i think, apart from the last part :

 *Quote:*   

> Some devices support more than one LUN (Logical Unit Number) in order
> 
> to allow access to several media, e.g. CD jukebox, USB card reader,
> 
> mobile phone in mass storage mode. This option forces the kernel to
> ...

 

maybe some hardware combination is leading to this or you have on of those "rare devices" ? 

try to remove all the fancy splash stuff from your loader and try to see if you get any output in your display so that you can have at least some sort of messages from your kernel. Or try to redirect the output to another computer f.ex.

There is also a max_lun parameter in case you want to mess with this just to see if it has any effect.

In any case i would let the kernel devs know about this issue, i don´t think this behaviour is "normal".

cheers

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## benny1967

OK, tried to start from a minimalistic GRUB configuration:

root (hd0,0)

kernel /boot/kernel-2.6.31-gentoo-r6 root=/dev/sda2

and then added the other parameters step by step.

I found out that this line was the culprit:

initrd /boot/fbsplash-livecd-2007.0-1024x768 

It should read

initrd (hd0,0)/boot/fbsplash-livecd-2007.0-1024x768 

Obviously, this was something I got away with before I changed the kernel configuration, but now it needs to be corrected. The Wiki also says (hd0,0) has to be included; this probably wasn't there when I copied the instructions 3+ years ago.  :Wink: 

Might not affect others and depend on how you manage your partitions, maybe?

Here it's

/dev/sda2 on / 

/dev/sda1 on /boot 

/dev/sdb3 on /home

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