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Unread postPosted: Tue Jun 07, 2005 11:49 am 
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edefault wrote:
Just curious:

is anybody planning to exchange a R5200 CPU with a R7900 to see if a patched PROM image will work?

And if yes, when eventually?



Walther,

Count me in for first batch of RM7900, hopefuly...
I have RM7000 board but was hasitating to go for 600MHz since is not exactly cheap and I have already R12k 400 o2, so it's not big gain for me.
RM7900 move makes more sense to me.

waiting to see some 7900 benchmarks :roll:

z


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Unread postPosted: Tue Jun 07, 2005 12:10 pm 
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jan-jaap wrote:
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Of course, if the RM7900 is not functionally identical to the RM7000, you're looking at a different problem. You'd have to write TLB and cache setup code and inject it into an existing PROM. Tricky business.

FWIW - The L2 and L3 cache can be turned off in the boot-time PROM program, I would say get the RM7900 chip running and address the cache and other issues later. It might be easier just to replace the PRId number of the RM7000 with the one from the RM7900 in the IP32PROM, write a new boot-time PROM program, burn a PROM chip, flash the IP32PROM to the O2 motherboard and see if the system will boot. If the O2 were booted from a terminal, it might be easier to tell what's going on as the system starts.


edefault wrote:
Quote:
Perhaps we´d to decide to go straight through and order R7900 CPUs instead?
(OK, just dreamin´)

Yes, just dreaming. :wink:
The RM7900 CPU chip swap is a "long term" project at the very best.

Joe


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Unread postPosted: Tue Jun 07, 2005 7:14 pm 
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I'm ignorant of the concept of checksums (exact byte count??), but I suspect it's safe to assume that the PROM image has one and that before the flash program will load it and flash do the upgrade it checks.

The only consequence I can see of hijacking the RM7000 settings is if any of the TLB exceptions or associated programing adds more data than it replaces then it would possibly affect execution if instructions point to a specific piece of code at a specific address. If the two are completely command compatible then there may be no hassle.

I've got the data sheet for the PROM chip so I'm going to sit down with a DMM later and see if I can find external contacts for programming the PROM. Common sense tells me there should be some, just gotta find them.

Has anyone with both a DUMP of the PROM as well as the actual PROM image that came with IRIX compared them to see if there are any differences?

Glenn


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Unread postPosted: Thu Jun 16, 2005 6:47 am 
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Awesome!!

*drooling*

So what's the next step in this project?


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Unread postPosted: Mon Dec 08, 2008 1:29 pm 
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Broadcom still make workstation-class multicore mips64 CPUs, but the interconnects are far more modern and so I doubt they could be shoehorned into SGI hardware. Irix could be ported to them though, if the source was ever to be released. Rumor has it it may have even been done internally at some point.

For now though, I think the MIPS Inc 1ghz r16000 is the fastest we'll see in sgi hardware.

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Unread postPosted: Wed Dec 10, 2008 10:53 am 
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How much faster theoretcaly can be RM7900@900 than R7000@600?

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Unread postPosted: Mon Dec 15, 2008 1:41 pm 
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bri3d wrote:
Rumor has it it may have even been done internally at some point.


Someone at SGI did design a new low-end which ran IRIX using a newer Broadcom dual-core MIPS CPU, but
I don't know what the clock was. I infer from what I was told that the unit was designed around PCIe, and had
an NVIDIA gfx card. It never went anywhere though, management killed it. :\

Joe once spoke of using the 1.5GHz Sandcraft CPU, but I can't remember now why he couldn't go anywhere
with it - probably needs the PROM source just like he does for the R9K/1GHz.

Ian.


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Unread postPosted: Mon Dec 15, 2008 9:59 pm 
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Where is this PROM located physically?
Any chance to reverse-engineer it?

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Unread postPosted: Tue Dec 16, 2008 3:07 am 
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edefault writes:
> Where is this PROM located physically?

Mbd somewhere. Dallas chip or elsewhere I guess.


> Any chance to reverse-engineer it?

Unlikely. If there was, I'm sure Joe would already have done it.

Last year I did ask a couple of SGI people about releasing the PROM source; the response was, never gonna
happen. Individual SGI employees might think it's a neat idea (they did) but it's not up to them.

Ian.


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Unread postPosted: Tue Dec 16, 2008 4:30 am 
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pretty sure Jan-Jaap actually decompiled the PROM, IIRC the output came to 10MB or so. Next issue was, no-one knew what changes to make...that may have changed in the meantime.


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Unread postPosted: Tue Dec 16, 2008 5:01 am 
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Is that decompiled image available somewhere on the net?

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Unread postPosted: Tue Dec 16, 2008 5:14 am 
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PARADOX to the rescue :!:

( Sorry, did I just say that?!?! <cough, cough> )

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Unread postPosted: Tue Dec 16, 2008 5:20 am 
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Indyboy wrote:
Is that decompiled image available somewhere on the net?

I'm not that stupid ;)

Disassembly may be allowed where I live, but distribution of copyrighted material certainly isn't.

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Unread postPosted: Tue Dec 16, 2008 9:12 am 
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ruckusman wrote:
pretty sure Jan-Jaap actually decompiled the PROM, IIRC the output came to 10MB or so. Next issue was, no-one knew what changes to make...that may have changed in the meantime.

Obviously reverse engineering the PROM is the start, but the main problem is that I believe the datasheet/manuals for the chip used in a 600MHz O2 were only available via agreement from PMC-Sierra. I think Chicago-Joe was given them, but said he didn't have the expertise to change the PROM. And PMC-Sierra watermark PDFs with the account, company and date/time when you download them, so you wont just find it leaked on an FTP server somewhere.


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Unread postPosted: Tue Dec 16, 2008 10:48 am 
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kramlq wrote:
And PMC-Sierra watermark PDFs with the account, company and date/time when you download them, so you wont just find it leaked on an FTP server somewhere.

That part even I could fix !


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