Hello,
I almost finished constructing LFS 6.6 but after rebooting it I got following error message:
cannot open root device "sda7" or unknown-block(2,0)
http://thumbsnap.com/vf/RMY8JA46.png

some information about my build:
->host computer : virtual machine running on vmware workstation with SCSI Hard drive (LSI Logic Adapter)
->host OS: kubuntu 9.10
->HDD partitions:
/dev/sda1 ext4 (kubuntu)
/dev/sda2 extended
/dev/sda5 ext4 (home partition)
/dev/sda6 swap
/dev/sda7 ext3 (LFS)

->LFS Linux kernel 2.6.32.7
-> /boot/grub/grub.cfg menu entry (on LFS partition):
{
insmod ext2
set root=(hd0,7)
linux /boot/vmlinux-2.6.32.7-lfs-6.6 root=/dev/sda7 ro
}

I think this problem related to SCSI Hard Drive but I don't exactly know which config flags should be set on kernel .config file for SCSI support, please help!

I've no idea what a vmware virtual machine is so I don't know if that is related to your problem but it looks to me like you need to work on your kernel config. Your Oops mentions RAID and NFS. Do you need to use them? If not, disable them in your kernel config. When you compile your new kernel, compile everything you think you'll need into the kernel. Don't use modules until you've got a working kernel. Find out what drivers you need. On your host system use lspci from pciutils. That should be your starting point. Compile support for everything it mentions into the kernel. Also on your host system use lsmod to see what modules it has loaded. make sure you compile all of them into the kernel. If you're not sure where to find how to enable those modules, read the help ? for each kernel option - it should say what the module it enables will be called. Read the kernel config from your host system - there should be a compressed copy at /proc/config.gz. Make sure you compile support for your root filesystem into the kernel.

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Shouldn't this be
AFAIK, numbering of the harddisks begins at (hd0,0) for sda1. So sda7 would be (hd0,6).
I am also not sure about
since you have an ext3 partition on sda7. I know ext3 is basically an ext2 fs extended by journalling feature, but you might want to keep it this in mind.

If my above suggestion does not solve your problem, you might want to consider recompiling your kernel with an existing .config that works. I compiled my first kernel with the configuration of my Ubuntu distro and it gave me no problems.

thank you from your help.
I used lspci command on host machine and found that it uses BusLogic Driver for SCSI storage controller so I enabled relevant flag on kernel config menu:
Device Drivers --> SCSI device support --> SCSI low-level drivers --> BusLogic SCSI support (CONFIG_SCSI_BUSLOGIC=y)
after making the kernel, instead of LFS grub, I used my kubuntu grub and add an entry for LFS:

title Gnu/Linux LFS 6.6
root (hd0,6)
kernel /boot/vmlinux-2.6.32.7-lfs-6.6 root=/dev/sda7 ro

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