werner at openmoko.org
Wed Apr 15 17:03:18 CEST 2009
Gerald A wrote:
> Debugging here is boot debugging, not application debugging, just to
> clarify, correct?
It's system-level debugging: boot loader, kernel ailments, mystery
freeze, etc. It can also be bug reports: if a user has a suspected
kernel problem, it's often nice if one can ask them to connect a
serial console and report what gets printed there, and when.
> My idea is old-school PC, the way they look for an MBR in a few different
> areas (hard disk,
> floppy) before launching into the code. We know by now that the boot flash
> doesn't change
> very often, usually hackers want to change the root and kernel images.
Sure, that's basically what the NOR does. Only that it uses u-boot
because that's what we had back then and writing a new boot loader
(e.g., Qi) would have taken much longer than adapting u-boot.
But again, the NOR has its cost. Even the chip itself is probably
about as expensive as IDBG, and it only gives you the debricking,
not all the other niceties.
The 6410 has a built-in boot ROM that does what you're describing.
So there you wouldn't need a debug board or an extra chip for
debricking. They would still be useful for debugging, though.
> Ok, dumb question: Does this mean we don't need a graphics chip at all?
2442: no, but you have very very fast access from the CPU to the
framebuffer. More than ten times faster than through the Glamo.
For a sensibly programmed GUI, an "unaccelerated" 2442 should run
circles around the Glamo. Idem for classical games.
6410: there are 2D and even 3D accelerator functions in the chip.
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