Anyone with experience in Cross-Compiling, especially to an embedded powerPC?

[Douglas Jerome]

On 05/13/14 16:04, Carruth, Rusty wrote:
> Ok, pardon my dumbness, but let me back up a bit.
>
> First, lets look at the switch/router things:
>
> (And I should first ask what flash controller is being used – does it
> automatically do ‘read scrub’ or other techniques to get around this
> whole issue?  If so, you don’t need to do anything…)
>
> Can you log in (as root, or become root) on the switches/routers?
>
> If so, can you ‘see’ all the files you’d have to change?
>
> If so, why not copy ‘in place’.  That is, copy the whole thing (or parts
> of it) to a new directory, then rename everything to the new place.
>
> So, for example, lets say you had /bin, /etc, and /var you wanted to do
> this to.  /bin has 200M, /etc has 10M, and /var has 1G.  Your flash has
> 2G free.
>
> So, ‘mkdir /bin.new /etc.new /var.new ; cd /bin ; tar cf – . | ( cd
> /bin.new && tar xf - ) ;cd /etc; tar cf – . | (cd /etc.new && tar xf -)
> ; cd /var ; tar cf - . | (cd /var.new && tar xf -)’
>
> That gets you 3 new dirs., /bin.new /etc.new and /var.new.  Do your MD5
> sums across the world and compare.
>
> Now, rename everything:  ‘mv /bin /bin.old ; /bin.old/mv /bin.new /bin ;
> mv /etc /etc.old ; mv /etc.new /etc ; mv /var /var.old ; mv /var.new /var’.
>
> Ok, so now new is new and old is old.  Delete old as you see fit, but
> probably after a reboot ;-)
>
> Beware that when you move /bin suddenly you won’t have mv available any
> more, so you have to say /bin.old/mv to be able to use it.
>
> No new kernel needed.
>
> On the other hand, if you have no choice but to make a kernel,
> ‘everything you need’ should be there when you get the kernel source.
> Other than special hardware that requires special drivers, just ‘build
> it and they will come’.  Or rather, build it and it will run.  All the
> majic of linking and all that is taken care of for you.  The only thing
> where absolute addresses is needed is (as far as I can remember right
> now) just hardware.
>
> Good luck, Mr Phelps!
>
> Rusty

If it that easy, then maybe migrate through the files in
something like 1K chunks with dd, writing the next 1K chunk
from the file in flash to a 1K file on RAM Disk then back.

I think this is just for the few files in /boot, to refresh
the kernel, yes?  The kernel is running in RAM, so you can
write to it the kernel binary file in /boot while running.