Scared of hard work ?

Posted Oct 13, 2010 9:40 UTC (Wed) by amimjf (guest, #506)
Parent article: HTC Willfully Violates the GPL in T-Mobile's New G2 Android Phone (Freedom to Tinker)

Looking into this the main problem they are claiming is that without the sources provided by HTC they cant properly control the eMMC chip.

Thats just plain rubbish, i do embedded development and they need to get hold of the datasheets and start wring code until they get the correct responses from the device. How do they think HTC created the driver/headers in the first place ?

The only 'technical barriers' are the skill and willingness to work on the part of the people involved.

Scared of hard work ?

Posted Oct 13, 2010 15:11 UTC (Wed) by bronson (subscriber, #4806) [Link] (3 responses)

Do you seriously think they ignored the data sheets??

The problem is that there are some magic values and complex interactions that aren't covered by the docs. As an embedded developer, I'm sure you've seen this situation hundreds of times. I know I have.

Your "technical barriers" sound like a tired election speech. How about incomplete docs? Or obfuscated layout (just try to bring up a RAMDAC if I swizzle the RSS lines on the PCB and don't tell you how)? Or crypto sigs? Or any of a number other things that would raise the required reverse-engineering work to years or decades? Those aren't technical barriers?

Scared of hard work ?

Posted Oct 14, 2010 8:11 UTC (Thu) by amimjf (guest, #506) [Link] (2 responses)

I've seen data sheets lacking detail on a couple of occasions in the last decade, so you just have to work it out for yourself. Data sheets are almost always very good in my experience.

I've never seen the inside of the phone they are reverse engineering, but unless there are FPGA's or ASIC's hiding certain parts of behavior you just have to trace out the lines from one component to another.

Take the example of a first prototype back from manufacture, it does not work at all, so what do you do ? you get your scope and follow the lines from one chip to another until you know where the fault is.

Anyhow this is all moot, the engineers at HTC have done all this once so anybody else with a similar level of skill can. All this episode shows is that the HTC guys are pretty good.

Scared of hard work ?

Posted Oct 14, 2010 17:40 UTC (Thu) by bronson (subscriber, #4806) [Link]

Everything looks easy when someone else is doing it.

Have you actually seen a modern cell phone PCB? It's all BGAs or worse. 80% of the traces are buried so they can't be probed without delaming, and even those on the surface are so small that you need specialized probes just to hit reliably. "Just scope it" isn't really an option anymore.

> HTC have done all this once so anybody else with a similar level of skill can.

And a similar access to SanDisk engineering support.

Scared of hard work ?

Posted Oct 18, 2010 0:38 UTC (Mon) by dmag (guest, #17775) [Link]

> Data sheets are almost always very good in my experience.

You haven't worked on enough ARM chips recently. These companies get a well documented ARM core, throw some custom peripherals on it and forget to document all the possible interactions. (Sharp, I'm looking at you.) I won't even mention the engrish in the datasheet, since I expect that nowadays.

> but unless there are FPGA's or ASIC's hiding certain parts of behavior

Today's modern ARM chips have so many functions per pin (always at least two, sometimes four) that the configuration code might be more valuable than a circuit diagram. even without an FPGA

> the engineers at HTC have done all this once so anybody else with a similar level of skill can

It sounds like you are saying "engineering and reverse engineering are the same effort." That's not even close to true.