Hi Alexander,

On Wed, Jun 28, 2017 at 1:46 PM, Alexander Kapshuk <alexander.kapshuk@gmail.com> wrote:
I am trying to setup a build environment where I can run the kernel and see how the changes I have made to the kernel source work.
My understanding, based on googling, is that it is common practice in the kernel community to use a virtualised environment for that purpose.
What I have done so far is create a ramfs that is built into the kernel, as described here [1] and here [2].


a). I have generated a minimal initramfs_list file:
scripts/gen_initramfs_list.sh -d >usr/initramfs_list
Which looks like this:
# This is a very simple, default initramfs

dir /dev 0755 0 0
nod /dev/console 0600 0 0 c 5 1
dir /root 0700 0 0
# file /kinit usr/kinit/kinit 0755 0 0
# slink /init kinit 0755 0 0
slink /bin/sh busybox 777 0 0
file /init /bin/busybox 755 0 0

b). Set CONFIG_INITRAMFS_SOURCE:
CONFIG_INITRAMFS_SOURCE="/home/sasha/linux/usr/initramfs_list"

c). And had the kernel generate the initramfs image:
make
...
GEN     usr/initramfs_data.cpio.gz
  CHK     include/generated/compile.h
  AS      usr/initramfs_data.o
  LD      usr/built-in.o
...

When I run the kernel in qemu I get an error message which complains about /etc/init.d/rcS missing.

Did you check initramfs for rc.S script?

The kernel configuration, busybox configuration and the layout of initramfs (which should be /home/sasha/linux/usr/initramfs_list) should be consistent. If the kernel is asking for it then it is not consistent.
 
The posts online seem to suggest that this has got to do with the busybox configuration.
So far, I have not been able to get my head around this problem.
Any points or suggestions would be much appreciated.

Alexander Kapshuk.


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Thank you.
Shahbaz Khan