11/8/11 Update: Updated keyfix kernel with the EI22 initramfs. Also, Samsung has placed the previous official (and now labeled EI22) source tarball on their opensource site.
10/24/11 Update: It appears that Samsung has removed the "official" Epic GB source tarball from their website. I've mirrored it for anyone interested in the original release. For anyone actually looking to build with the sources, you're probably better off using Rodderik's GitHub
10/19/11 Update: As everyone's found out by now, Samsung released official Epic GB sources last night. There's not that many changes to our device in the official source tree compared to the previous, but a few appear to be subtlely important (see abbreviated deltas). It still needs some work to get into a buildable state, but it does appear to work great on EH17!
I've updated most of my patches for GB, conveniently packaged together. I've also uploaded a new EH17 kernel that works on stock (rfs) EH17 ROMs and includes the keyboard fixes with optimized values, along with userdebug and kexec support. Feel free to give it a try.
Meanwhile Rodderik is updating his GitHub repo to include all these patches for folks to clone from, stay tuned.
So apparently when Samsung released the kernel sources to the Mesmerize's Gingerbread update a month-and-a-half ago, that source tree contained almost-buildable kernel sources for our device as well.
I've patched the sources (removed modemctl definition, added tfsr driver, compile right camera driver) to build for the Epic. I've also built a custom EH17 kernel combining these sources with the EH17 initramfs. It's essentially stock EH17 with ro.debugging=1, adbd always-spawning during recovery, and testkey signature verification. I'll get to porting over some other patches (like the dropped key fix) soon.
As for compatibility with EH17, the source tree itself appears to have been checked out on 8/30 and looks to include everything EH17 does. I ran "strings Image | sort -u" on both kernels to make sure there weren't any obvious strings/symbol differences between them. The ones that remain appear to be minor, but legitimate fixes.
Thanks to jt1134 & Rodderik for pointing out that the Mesmerize source released contained Epic code, and Tortel & ugothakd for testing.
GitHub repo, thanks Rodderik!
Run "make mrproper" to get rid of
Patch to complete Epic support.
Build with EH17 initramfs as usual, use victory_8G_defconfig for kernel configuration.
Official GB sources: SPH-D700_GB_Opensource.zip (originally posted on opensource.samsung.com, since removed.)
Epic GB source patches: kernel-GB-3a-patches.tar.gz
Source-compiled, keyboard fix EI22 kernel: kernel-GB-3a.tar.md5
(URLs for Mesmerize tree patches removed, although they're still valid.)