On 09/09/2019 12:54, Bruce Dubbs wrote:
On 9/9/19 5:23 AM, Vaughan Butler wrote:
Hoping for some help with kernel panic problem after building LFS 8.4.
The same thing happened with 8.3, and I could only get that build to
run by copying over the 4.18.x kernel files from my laptop ( Linux
Mint ).
I haven't got a dump of the error, as it occurs very early in the boot
process, and locks the machine, but the key line appears to be
3.9822431] ---[ end Kernel panic - not syncing: VFS: Unable to mount
root fs on unknown-block(0,0) ]---
I've spent a lot of time looking up this issue in various online
forums, and have tried recompiling the kernel in several different
ways, but without success. I suspect this may have something to do
with the host system, even though I built 8.4 using the 8.3 build as
host ( I realise this may be irrelevant, as the 8.3 system is after
all using the same kernel as the Linux Mint on the laptop ).
There are a couple of ways to going about fixing this type of problem.
The 'Unable to mount root" problem is almost always due to a missing
driver in the kernel. Since we do not use an initrd, it must be
compiled into the kernel.
Probably the easiest way to solve this is to configure the kernel with
make defconfig
See the output from 'make help' for a description and other options.
In some cases, the above may not work, then another way is to boot to a
known good system (e.g. mint} and do 'lsmod' (the list may be fairly
long). Use the output to see what modules they are loading and then go
though the 'make menuconfig' procedure and find the matching options.
Then make sure your configuration builds them but not as modules. Check
especially for things like:
CONFIG_ATA=y
CONFIG_ATA_VERBOSE_ERROR=y
CONFIG_ATA_ACPI=y
CONFIG_SATA_PMP=y
CONFIG_SATA_AHCI=y
and
CONFIG_EXT4_FS=y
CONFIG_EXT4_USE_FOR_EXT2=y
CONFIG_EXT4_FS_POSIX_ACL=y
CONFIG_EXT4_FS_SECURITY=y
assuming you are using an ext4 root partition.
-- Bruce
Thanks Bruce, I've been trying to follow a strategy of this sort. Make
defconfig didn't work, so I was looking for a way to identify what items
were modularised in make menuconfig, in order to change them to built
in. Seems there is no quick way to do that, so I'll follow your method.
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