Any Update On 2nd Cpu?

[x68000]

this was the most intelligent thread on the site outside of the devs section and some sausage eaters and army knife makers had to come and spoil it.

 

[Mr. Anderson]

yeah it's dead now, however I don't think there was much more to discuss at this point.

 

[chris_r]

My father speaks it with a bavarian dialect, yet Im learning hoch deutch.

​

Ive been learning german for oveer 6 years now. How do I know what sort of dialect Im picking up?

 

[Mr. Anderson]

If you where really learning "german" then you shouldn't have any dialect(at least not in writing something in german, you sure have a little dialect to your native language, only few people can speak a foreign language without any clues to what their native one is). German isn't that hard to speak but writing german with the correct spelling and without any errors, is even for people born with a pretty big challenge

 

[dwelch]

5) Using the 940T core in Linux for other tasks apart from video processing is a bit difficult, but as Squidge has shown, it is possible. In HH mode (or direct hardware, or whatever) it is trivially easy to use the 940T core.

You may have seen my other posts, emails, whatever. I am very interested in the state of HH on the gp2x, have sdk2x from december, need just a touch of handholding to get me over the hump and then I will be able to help out greatly in the HH effort (although I may do it my own even lower level way (sdk2x is high level to me as it is a big library trying to replace file i/o, sd, etc all in one place, anyway...). Some may remember me from the GBA or iPod (did what you call HH on the iPod, ported Asteroids, did a little second cpu stuff).

Anyway, here is what I am looking for today, and forgive me for only reading half of this thread as my answers may be in the other half. An example, like the dual cpu example posted in this form (speaking of, I just looked and I cannot unzip those files, I wonder if it is me or the files are gone/corrupt, I was relying on them)
Okay, again, cpu 1 halts cpu2, copies cpu2 program to cpu2 memory, starts cpu2 executing, one or the other halts cpu1. cpu 2 draws some pixels on the display (that is the key element I need a boost with, give me some pixels I can take care of getting scrolling text up there and I am off to the races). I am EXTREMELY comfortable with or without vector tables, interrupt handlers, although, unfortunately, a little rusty. Also building my own gcc is preferred so that I have control over where everything goes, what is in there and what isnt, etc. Quite comfortable there. And if you have seen my work, you will know that the first things I plan to understand are performace (using dhrystone, I know, no need to discuss it), with cache on/off, perhaps with the other cpu running or not, clock speeds, various versions of gcc. Hopefully ARM's tools if I can get them running again (probably not), etc.

Thanks,
David

 

[Draco]

There is a reason bumping old threads is frowned upon, I think you could've just opened a new thread for this...

 

[gaterooze]

Hi David, and welcome to the board!

It would be a good idea to start a thread in the GP2X Developer's Forum here, as you will get faster/better answers there from the the people in the know.

Best of luck, hope you can help out.

 

[torpor]

The thing is, the 2nd Core is useful for *tons* of things .. think of all the libs you can stuff on it .. I for one am waiting to get a few other things sorted (MidiShareGP2X release) and then I'll have a look at what it would take to get libJudy, at least, usable on CPU2 .. imagine putting all your hard hash work on the 2nd CPU (good for AI and path-finding and other interesting mechanics) while CPU1 does all the device/IO ..

Its not useless. Its not un-usable. It is there, and can be approached by most competent Linux coders. And it won't be long until using the 2nd CPU is as easy as linking to libpthread or some other such ancilliary lib is for the average programmer.. in other words, pretty easy.

 

[DaveC]

The thing is, the 2nd Core is useful for *tons* of things .. think of all the libs you can stuff on it .. I for one am waiting to get a few other things sorted (MidiShareGP2X release) and then I'll have a look at what it would take to get libJudy, at least, usable on CPU2 .. imagine putting all your hard hash work on the 2nd CPU (good for AI and path-finding and other interesting mechanics) while CPU1 does all the device/IO ..

Its not useless. Its not un-usable. It is there, and can be approached by most competent Linux coders. And it won't be long until using the 2nd CPU is as easy as linking to libpthread or some other such ancilliary lib is for the average programmer.. in other words, pretty easy.

I read Vobbo said the second core was pretty useless. He wrote an entire emu in ASM. He must know something right? Or maybe he didn't try it long enough?

I have heard both sides of this. Some say the small cache, memory contention and lack of a MMU make the second core useless mainly for emus. Others say it can be useful for something. Maybe it is useless for emulation but good for other things?

 

[Emu&Co]

We'll see. Some said PSX Emulation is impossible and now I can play Legend of Mana quite fast. Lets wait some months and we'll have a 400 MHz (In theory/ ~300MHz is more realistic) GP2X. Believe me. I am a notoric optimist.

 

[vobboomg]

The thing is, the 2nd Core is useful for *tons* of things .. think of all the libs you can stuff on it .. I for one am waiting to get a few other things sorted (MidiShareGP2X release) and then I'll have a look at what it would take to get libJudy, at least, usable on CPU2 .. imagine putting all your hard hash work on the 2nd CPU (good for AI and path-finding and other interesting mechanics) while CPU1 does all the device/IO ..

Its not useless. Its not un-usable. It is there, and can be approached by most competent Linux coders. And it won't be long until using the 2nd CPU is as easy as linking to libpthread or some other such ancilliary lib is for the average programmer.. in other words, pretty easy.

I read Vobbo said the second core was pretty useless. He wrote an entire emu in ASM. He must know something right? Or maybe he didn't try it long enough?

I have heard both sides of this. Some say the small cache, memory contention and lack of a MMU make the second core useless mainly for emus. Others say it can be useful for something. Maybe it is useless for emulation but good for other things?

Its not 100% useless....!

I`m actually trying to use it in hu6280 at the moment.... With careful programming it IS possible to farm some work over to the second cpu - Its not easy to do, and choosing the right task for the second cpu is very important...

I tried moving over my scanline rendering code to the second cpu and the emu ran SLOWER than using just one cpu.... But now I have found a suitable job for the second cpu when emulating the supergrafix... I`m getting a considerable speedboost now....!


Vobbo h34r:

 

[DaveN]

I tried moving over my scanline rendering code to the second cpu and the emu ran SLOWER than using just one cpu.... But now I have found a suitable job for the second cpu when emulating the supergrafix... I`m getting a considerable speedboost now....!

Vobbo h34r:

Fantastic!
The things like the mmu hack, the psx emu and finally a good way to use the 2nd cpu are showing us that the gp2x hasn't reached it's potential yet.
And I mean, the gp2x exist since last november and the official release also wasn't too long ago and more and more people seem to get interested in the gp2x. There's a big future for this device

 

[Vollgasasi]

vobbo i hope you share your progress in detail with other devs! rock on dude

 

[Epicenter]

The biggest thing to remember is that this 2nd CPU is really more of a bonus to the SoC used in the GP2X-- not a core, essential feature that if it is not easy to operate the machine is 'useless'. The main CPU is extremely powerful; whatever can be done with the 940T is free extra performance. Remember even if XGP units add decent 3D functionality they still will lose the 940T, and I'm sure this will be a notable loss not far in the future.