From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Landley Subject: Re: [DISCUSSION] Running linux-hexagon on the Qualcomm Galaxy S3? Date: Sat, 16 Feb 2013 21:37:57 -0600 Message-ID: <1361072277.11760.2@driftwood> References: Mime-Version: 1.0 Content-Transfer-Encoding: 8BIT Return-path: In-Reply-To: (from erappleman@gmail.com on Thu Feb 14 01:29:14 2013) Content-Disposition: inline Sender: linux-hexagon-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii"; delsp="Yes"; format="Flowed" To: Eric Appleman Cc: linux-hexagon@vger.kernel.org On 02/14/2013 01:29:14 AM, Eric Appleman wrote: > Good idea? Bad idea? > > A bunch of people Freenode (#d2common and #htc-linux) have begun a > port. > > https://github.com/detule/linux-hexagon > > Thoughts? Please keep me in the loop! The trick is: A) Getting a bootloader that runs hexagon code. In snapdragon there are 4 processors, and the "boot processor" is actually an old armv5l that bogs off to run radio code after initial boot. It has to hand off control to another processor, by default this is the Scorpion Armv7, it has to be reprogrammed to instead wake up the hexagon and give it control. 2) Last I checked some of the Snapdragon SoC drivers were only in the Android tree, under arch/arm. The hexagon will need these moved to a generic directory in the vanilla tree so hexagon can find the USB port and stick a serial console on it. (USB gadget for the win!) III) Qualcomm's soft MMU code is binary-only because their lawyers think nobody's ever done a soft MMU before and thus their patents on it won't be invalidated if it's a secret what they are. (Last I checked objdump could disassemble the magic instructions, there was just no documentation on TLB loading and such.) Also, back in 2010 there was a brief effort to get hexagon support in QEMU (just one thread, but it had to do the 4-issue VLIW since the different cores run different instructions and there's synchronization issues with jumps and such), which would simplify open source development _enormously_. Alas, it did not bear fruit that I'm aware of. Adding Hexagon support to TCG would be awesome. Rob