initramfs problem: can't replace motd

Altera_Forum · ‎10-28-2009

Let me ask a really dumb question...

Why can't I replace the /etc/motd file with my own?

I'm using pretty much the default kernel and app config of uClinux which means all the files in uClinux-dist/romfs/ are going to be my file system after compilation.

I've had success building simple stand alone executables and throwing them in the /bin directory, but this is the first time I've tried to make a modification to an existing file. I figured motd is appropriate as it has no effect on the system other than being printed at boot time, and the results are easy to see.

Before compilation I replace uClinux-dist/romfs/etc/motd with my own. When I run make, somewhere along the line it gets completely replaced.

In trying to figure out where the source file is, I changed the permissions of the motd to 000 to force an error on compilation when it attempts to overwrite. This only brought me to /uClinux-dist/linux-2.6.x/usr/initramfs_data.cpio.gz which is an archive I can't open because my OS doesn't know what a cpio file is.

I tried removing the line "../romfs/etc/motd \" from /uClinux-dist/linux-2.6.x/usr/.initramfs_data.cpio.d in hopes it would ignore the motd file after that. No Luck, it came back.

Can someone shed some light on this mystery?

Thanks,

Todd

Altera_Forum · ‎10-28-2009

eltoddo,

You might be better off by changing the last line of your board's "rc" script to call your own program instead of "motd".

The nios2 "rc" script is located in the .../nios2-linux/uClinux-dist/vendors/Altera/nios2 directory. The last line reads "cat /etc/motd".

Good Huntin'

cb

Altera_Forum · ‎10-28-2009

Good suggestion cb,

I originally tried editing the romfs/etc/rc file and found that it was also replaced. I just assumed that the file was also overwritten by the same mysterious force that motd is.

Changing the rc file in the location you suggested worked and allowed me to change the output to motd.alt. So the work-around allowed me to accomplish using a different file.

Still, I really don't like the idea of motd being replaced/generated by a source file which I have no idea where it comes from. Now I question which other files I make changes to will be blown away by rebuilding the kernel.

If anyone knows where motd is generated/copied from please let me know so I can have some idea of what changes I can make and which I can't.

Cheers,

Todd

Altera_Forum · ‎10-28-2009

Please change the files at

nios2-linux/uClinux-dist/vendors/Altera/nios2

They are copied to romfs/etc when making "romfs" target.

- Hippo

Altera_Forum · ‎10-29-2009

Hi Hippo,

Thanks for the heads up on that directory. That addresses a whole bunch of the files I'll be after soon. But the motd file is unaccounted for.

Something must either generate it or copy it's contents from another file. Could it be decompressed out of an archive?

Altera_Forum · ‎10-29-2009

I think anything not in the specific vendor directory is in vendors/Generic/romfs/

Altera_Forum · ‎11-03-2009

Hey ykozlov,

Good catch! Sure enough the motd file there, if changed, will be put in romfs in the kernel image file.

I'm pretty sure I tried modifying each 'motd' file in the uClinux-dist folder tree. Oh well, I guess I missed this one somehow.

Nice to have closure on this.

Cheers!

Altera_Forum · ‎11-03-2009

IMHO, the correct way is to create the file in your vendors/* directory and modify the make file there accordingly.

Moreover at best you create your own vendors/* directory.

-Michael