New debug kernel installation mechanism committed to HEAD

[Andrew Atrens]

Hi Matt,

>     I realized something very interesting while doing the work, and that
>     is the backup kernel and modules created when you installkernel are
>     not stripped of their debug info, which means that one will often wind
>     up with 3+40 = 43 MB of *BACKUP* kernel and module data after an
>     install kernel under the old regime.

:)

> 
>     The new kernel install rules will automatically strip the debug info
>     from the backup copies even while saving the fully debug kernel as
>     /kernel, reducing the space used by the backups from ~43MB to ~13MB,
>     saving ~30MB, while only eating an additional ~10MB for the new
>     debug-enabled /kernel.

I like this plan much better than my strip-all-the-modules plan :)

Btw, is there a how-to somewhere on how one would load a kernel module
into gdb to do post-mortem on a vmcore? If one can't do this, then having
debug info in modules would definitely be less useful.

Should this work? -

gdb -k kernel.0 vmcore.0
gdb> add-symbol-file /nvidia.ko 0xc060d000
gdb> bt


>     So, believe it or not, for people who do 'installkernel' a lot with
>     debug kernels, these changes will actually save you ~20MB of disk
>     space
>     in the root partition even though /kernel is 10MB bigger!!  Now is
>     that cool or what?

Yep, very cool indeed. :)

Andrew.