After having finished LFS, it is time to boot it ,but druing boot lfs, log show as follows:
"Kernel panic -not syncing:VFS unable to mount root fs on unknown-block(0,0)"

this is our information:
our lfs is built on /dev/sda3.
we boot lfs from grub by using the following command
"grub> linux (hd0, msdos3)/boot/vmlinuz-4.9.9-lfs-8.0-systemd root=/dev/sda3 ro"
grub>boot
"

we use SCSI disk ,but before make kernel, I have checked the menu config about scsi driver, we have add this options.

so we ask someone help me ,thanks.

Besides disk driver, you also need a filesystem driver and scsi generic drivers built into kernel.

Yes, the kernel, using only drivers that are built into it (since you're not using the initrd hack) must contain all of the drivers needed both to communicate with the hardware and to understand the file-system that it will find there.

For convenience, I ordinarily build into the kernel all of the filesystem and hardware drivers that I know that I might encounter, such as FAT32 on your garden-variety USB stick. (Filesystem drivers used for removable devices can also, of course, be modules that will be loaded by hotplug/coldplug on demand ... but they're really not that big, anyhow.)

according to wait you said, and all scsi driver and filesystem, but the error still exist

my vm version：12.5.2 build-4638234。 does vm exist some other error?

thank you!

lfs boot successfully !!!