OSDev.org

Its been one of those days.. you know, when certain people dont phone you back, your mountain bike gets a flat tyre (that you shoulda fixed yesterday..) etc..

Well I have been reading the sparc-v8 instruction set manual and well...

I'm writing a SPARC emulator (sun4m architecture based).. Like I have nothing else to do.. heh ::)

aaanyways, i want it to be like bochs, a real emulator, letting people do osdev for sparcs (i like sparc boxes).. and Id rather try something simple (sparc32) before (if ever), going on to sparc64 emulation...

the hardest part is going to be writing a fake OBP firmware/rom.. and getting that interfaced into the emulator... I'm sure I can work something out (illegal opcode probably...)

(simics costs 1500 to buy..)
there is one other gnu sparc em around I know of, but its quite old and is not a real emu, just enough to boot homemade programs really.. (isem).

instruction set looks pretty simple.. so... we will see...

why is it there is no documentation (Freely) available on an 'open' standard?? grrrr...

no info on the net anywhere, and I wont pay the IEEE 168$usd just to view a PDF file of an OPEN standard....

aaaaargh. trust sun to have removed all docs on SBUS from their site.

Why not just get an image of the firmware ROM and figure out the hardware from there?

It's a lot of work, but sometimes it's what you have to do.

you cant get sun OBP roms/firmware updates. they come as patches, not plain roms.

i'm going over netbsd sbus control code to work out what they are doing so I can work out what I need to provide..

i just want to rant off here but...

you know when you spend an ENTIRE day writing some code, thats hellishly complex, and dman nasty, that when you step back and look at it, you realise you could do it all in about 10 minutes and in 1/100 the lines... AAAAAAAAAAAAAAAAAAAAAARGH!!

i spent a whole day writing a complex interface and code for the SBUS when now I look at it I can achieve the same thing in a far far simpler way in shitloads less lines of code and without any bugs?

i'm pissed...

design is one thing, implementation is another..

rm -rf sbus.c

hey, don't be pissed, gosh! you get it working, stout lad thou' you are!

i'm not quite sure to get what's happening here ... what's an OBP ? kinda BIOS ?

The OBP, I'm assuming, is the OpenBoot PROM, which is, yes, the BIOS for the pre-OpenFirmeare Sun computers, starting at around the sun3 / sun4 era.

And if you can only get patches from Sun, why not either: 1. Write a program to just dump the ROM that's in the computer to disk or 2. Pry the ROM chip off the motherboard and put it in a ROM burner to read the contents off?

you can get openfirmware patches, but afaik no obp patches.
and roms in sparcs are solid. not eeproms. so no rom updats were issued.,

Jamethiel sounds right ... why don't you just read out the rom chip ? even if this can't be done in pure software on the machine, all you'd have to do is generate addresses on its pins, do a read cycle and get the output ... doesn't sound that complicated, does it ?