In many cases (test certain modules, first boot-ups, DDR is not available), writing bare-metal (SDK) code with runs on iRAM (OCRAM) is the only possible scenario. The first (attached) patch creates a new linker file with proper sections and the second includes a tiny app (it should be tiny, by definition) using the previous file. These are the steps to have the setup ready:
1. Dowload latest i.MX6 SDK (v1.1.0 is the latest when writing this document).
2. Let GIT take the control (git init; git add .; git commit -m '1st commit')
3. Apply patches (git am < patch1; git am < patch2 )
4. Compile
# This example is intended for a mx6q sabreSD, revision C
$ ./tools/build_sdk -target=mx6dq \
-board=smart_device \
-board_rev=c \
-app=iram
5. SD Card Flashing & Running:
5.1. ELF file & U-boot:
# Output image is located on:
# elf=output/mx6dq/minimal/smart_device_rev_c/minimal.elf
$ dd if=$elf \
of=/dev/sdb \
seek=2048 bs=512; sync
# Boot your board with your favorite u-boot version, just make
# sure the bootelf command is presnet
> mmc dev Y
> mmc read 0x10800000 0x800 XXX
> bootelf 0x10800000
where Y is the SD device and XXX are the records seen when dd flashing.
5.2 BIN file:
# Output image is located on:
# bin=output/mx6dq/minimal/smart_device_rev_c/minimal.bin
$ dd if=$bin \
of=/dev/sdb \
seek=2 skip=2 bs=512; sync
# Place the SD into your board and power-on.
NOTES:
+ The first patch was taken from the internal discussion MX6 SDK (PLATLIB): has anyone created a stripped down version that will run from internal RAM?
