Is Complete Control Over The Hardware Possible?

[Simon]

Hi all

Just wondering: is it possible to 'switch out' linux and take full control of the hardware?

I like bit-banging bare metal

If so, does anyone 1) know how and 2) have a decent memory map?

Thanks

 

[slygamer]

Hi all

Just wondering: is it possible to 'switch out' linux and take full control of the hardware?

I like bit-banging bare metal

If so, does anyone 1) know how and 2) have a decent memory map?

Thanks

HH SDK is where the hardcore SDK seems to have finished up over a year ago. There wasn't much benefit that it gave over having the program run in Linux. Here's a quote from July about the state of the HH SDK...

The easiest way to take over the machine is to stick a routine in the reset vector and cause a watchdog timeout.

HH was thought to be the best way forwards to get the most performance out of the machine. However, with some hacking, we can get almost identical performance from linux, and reap all the benefits of linux as well (easier developing & debugging, ready made libraries & device drivers, etc).

HH-mode just isn't necessary any more, and with more and more people wanting to use the usb networking and mass storage features (to run apps and stuff from external harddisks, pendrives, etc) it is becoming inpractical.

Of course, if your only interested in HH-mode, then the best way to go is probably by grabbing the latest SDK (still Dec'05 I think), hacking up a u-boot to stop it from booting linux, and uploading your code direct to memory via uboots binary load commands, and executing it from there.

Here is a fairly accurate memory map.

 

[Simon]

hmmm, interesting. Im not sure Id agree performance would be the same - well written assembler banging hardware directly would *have* to be better than C on linux......especially when attempting to use the 2nd cpu?

Anyhoo, thanks alot - some interesting reading afoot.

 

[Klepto]

Yes, it's very possible. I'm (still) planning on a native forth for the gp2x. Real life keeps getting in the way so progress is painfully slow, it's mostly still at the vapourware stage.

 

[Squidge]

hmmm, interesting. Im not sure Id agree performance would be the same - well written assembler banging hardware directly would *have* to be better than C on linux......especially when attempting to use the 2nd cpu?

Anyhoo, thanks alot - some interesting reading afoot.

You can run your well written assembler in Linux, and most of the time, you can still bang the hardware directly as well. Just because there's the "Linux way" and the "SDL way" doesn't mean you have to use them You can also use the 2nd cpu easily enough.

There's a marginal advantage of dropping Linux completely of course, but it isn't worth it considering the added complexity in writing/debugging and running the code.