Breaking Free the Gumstix DSP
Following the instructions on the DSPBridge Project (located at www.omappedia.org/wiki/DSPBridge_Project) for compiling the userspace files will work as long as the $DEPOT, $CROSS_COMPILE and the modified $PATH variables are set in the terminal as mentioned previously. Issue the make all command to get the full DSPBridge project samples, MPU API and DSPBridge library.
The Gumstix bootable SDRAM card should be split into two partitions: one containing the MLO, U-BOOT.bin and uImage, and the other containing the root filesystem (rootfs).
Using a bootable SDRAM card configured for the Gumstix Overo Fire, reformat the section with the current rootfs. Next, go to cumulus.gumstix.org/images/angstrom/factory/ and download the rootfs-booted-Overo-201004270808.tar.bz2 package for the Gumstix from the factory images. Now, uncompress rootfs-booted-Overo-201004270808.tar.bz2 into the rootfs partition on the SDRAM card.
After the rootfs-booted-Overo-201004270808.tar.bz2 package has been fully uncompressed, uncompress the production directory into the rootfs partition. If uncompressing the production directory into the partition created a new directory, move all the files out of the new directory into the same directory as the files with rootfs-booted-Overo-201004270808.tar.bz2. This should leave two directories inside the production directory: the usr and lib directories. Recursively copy the contents of these directories into the usr and lib directory of the uncompressed rootfs-booted-Overo-201004270808.tar.bz2. Now remove the uImage-2.6.33 in the boot/ directory of rootfs-booted-Overo-201004270808.tar.bz2 and copy the new uImage from the arch/arm/boot directory. Finally, change directory into the SDRAM card's bootable partition. Following the Gumstix site tutorial, this directory should be named FAT. Remove the uImage and copy the new uImage from the arch/arm/boot directory. Now unmount the SDRAM card and place it in the Gumstix and boot from the SDRAM card.
Once the new kernel has completed the boot sequence, add a password to the root user and secure copy the contents of the target/ directory of the userspace DSPBridge directories to the Gumstix. (The directories should be dspbridge/ and lib/.) Next, recursively copy the contents of the lib/ directory to the root /lib/ directory of the Gumstix and reboot the Gumstix. After the Gumstix reboots, enter the dspbridge/ directory and issue the ./ping.out command to receive the error shown in Figure 5.
This means the libraries have installed properly and the DSP device is detected. Now, load the base image for the DSP by issuing the ./cexec.out ddspbase_tiomap3430.dof64P and the ./cexec.out dynbase_tiomap3430.dof64P command. (To learn the difference, read the description at the bottom of the DSPBridge Project Wiki.)
Next, register the base image with ./dynreg.out -r <sample>dyn_3430.dll64P for the test you want to run. For example, register the ping sample DSP program using the ./dynreg.out -r pingdyn_3430.dll64P command, and execute it with ./ping.out. The output should look like Figure 6.
This output proves the kernel has been compiled successfully with userspace files for the Gumstix Overo Fire and that the libraries have been integrated into the rootfs. Finally, this proves that the DSP is operational because of the response from the DSP to the ping program. The Gumstix with the newly compiled kernel now can be used as a test bed for projects involving the DSP. I hope this tutorial has helped in understanding and implementing the compilation of the Gumstix Overo Fire's Linux 2.6.33 with support for the DSP.
James McColl is a Cadet majoring in Computer Science at the United States Military Academy at West Point, which was the best decision he made in college, and he's never looked back. Please direct comments to firstname.lastname@example.org.
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