Rink, thanks for the thorough repose, I haven't had a chance to test it out but plan to very soon. In the meantime, I used the solution from this thread
I also have been working through the scattered details of how to get UART 2 to be exposed to pins of the Gumstix Overo which are reffered to as GPIO 144-147 (146: TX, 147: RX, 144: CTS, 145: RTS) on various schematic diagrams and pinout tables. I just got it to work in the last hour (I actually subscribed to the list just so I could reply to your message). I got RX/TX working, I will try CTS and RTS soon (I need them). I found the following website very, very helpful with the detailed instructions you are looking for:
The page guides you through how to use bitbake to build a patched u-boot. It also explains how to build u-boot from the cross-compilation tools using 'make' and the compilers directly. I will say this, I tried to use the bitbake way and make a patch -- I for some reason couldn't make it happen -- perhaps I didn't have something set up right. Ultimately, I ended up using the section that explains how to do it WITHOUT bitbake, modified the overo.h file directly, did the make commands as described, copied the u-boot over to my microsd, and my uart2 now works on the described pins.
I don't know if this is critical (sometimes u-boot uImage, the rootfs have to be synced?) but in my case I built all of the files MLO, u-boot, uImage, and the root file system using bitbake first, and after trying to do the patch with bitbake and failing to get UART 2 exposed, I built just u-boot without bitbake and copied that to the microsd. Mine is thankfully working.
I hope that helps. That website seems to have several Overo related "how-tos" that may be of use to you as well.
http://gumstix.8.n6.nabble.com/Using-UART-2-on-an-Overo-tp660403p4966028.htmlIf you reply to this email, your message will be added to the discussion below: