[ELDK] No uImage in build images directory

[Larry Baker]

Wolfgang,

>> I found that the zImage was a byproduct of enabling the QEMU tests in my conf file.
>> The default kernel image format is supposed to be uImage.  I think enabling a QEMU
>> test overrides that to use zImage kernel format.
> 
> You cannot just enable qemu support for an arbitrary MACHINE setting -
> you must define your own machine, making sure that you include only
> such peripheral support (i. e. drivers) for which emulation under qemu
> exists.
> 
>> When I first set up ELDK, I examined the conf file to see what options were available.
>> I found the option to test the build using QEMU.  I liked that idea, so I enabled it.
>> When I did the bitbake for generic-armv5te core-image-basic , it failed because there is
>> no recipe for the QEMU test.  Even after I removed that choice in my conf file, bitbake
>> was still using the previous kernel format and rootfs format settings left over from
>> when I had enabled the QEMU testing.  It was only after I completely wiped out all
>> the files in my build directory and started over that bitbake made a uImage kernel and
>> not a zImage kernel.
> 
> When making any significant changes to the configuration, it is
> usually best to throw away the whole build tree and restart from
> scratch.
> 
>> I had a similar experience later (see my conversations with Detlev) when bitbake did
>> not pick up one of my modifications and I had to wipe everything out and start over.
> 
> Actually this is the most reliable way to make sure you get what you
> configured (which may still be different from what you want).
> 
>> I cannot always tell when bitbake is using cached configuration data and when it
>> will do a rebuild.  When in doubt, I wipe everything out now.
> 
> ACK.

Yes, all of your recommendations are practices I learned to follow.  Though, I wish it were
clearer when I could rely on bitbake to pick up the changes properly.  That would have saved
me many hours (my rebuilds from scratch take 3 hours).

Regarding the caution that you cannot expect QEMU support to work, I suggest adding words
to this effect in the instructions on http://www.denx.de/wiki/view/ELDK-5/EldkBuilding.
I have no previous experience using bitbake, and I followed these instructions literally.
Where the instructions say:

> You can now edit "conf/local.conf" to make any local adjustments you want.

I took this to mean that I could enable any features in the template conf file.  After all, the
template file comes from meta-eldk, not meta.

I suggest adding words to the instructions about the things that should not be enabled,
like requesting QEMU testing.  Or, remove those sections from the ELDK template conf file.

Similarly, I found I had to issue the source oe-init-build-env command, plus source the
edited set-path, every time I logged in.  I suggest adding this useful information to the
instructions as well.

Larry Baker
US Geological Survey
650-329-5608
baker at usgs.gov