Problems starting up system on a MPC823FADS

I've done some configuration changes, too. I adopted arch/ppc/config.in to support MPC823 (CONFIG_823) and added CONFIG_FADS (wich I found in your sources) to the machine types. I admit I didn't care about any other 8xx variants :-( but I tried to bring in all modifications and additions with appropriate #define's. So I'd be interested in your configurational changes!

I tracked down some strange behaviour regarding my dear fried 'printk' and discovered erratic behaviour when using the data cache of my MPC823. Since I think I had even problems using the instruction cache - unfortunately not reproducable - I turned off any cache and - wow - my data were consistent again! Nevertheless my MPC823FADS refuses to execute /sbin/init, but since my confidence in MPC823 Rev.0 (!!!) vanished completely, I ordered an upgrade to the latest processor revision at Motorola (since there are troubles with the built in video-controller, too!). Hopefully I get the samples before Xmas to be able to start my investigations again ;-)

BTW, to load my compressed kernel image, the Makefile (make zImage) in arch/ppc/boot adds a section containing the image to the boot code. My MPC8BUG refuses to download that section, it just silently ignores it. I circumvented this problem by compiling in the image via 'od' and 'sed' magic. Do you know any possibility to get MPC8BUG to load the additional section?

-- Helmut

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Almost all of CONFIG_MBX has become a generic CONFIG_8xx #define. Instead of having files include board specific information (like asm/mbx.h or asm/fads.h) they now just include asm/mpc8xx.h and this file has the board specific CONFIG_xxx stuff in them.

I am also going to reconfigure the processors so their IMMRs are all the same at boot time. Then all that remains are board specific I/O addresses. This should allow any 8xx board to be quickly ported, then you can add the unique I/O in the warm and fuzzy feeling that you can at least boot a kernel.

Damn....there are lots of weird silicon bug surrounding the data cache. I have the code that will work around most of them, but I have not yet seen anything that runs differently whether or not I include these changes. The 860 is affected the worst, and at _exactly_ 50 MHz and _exactly_ 3.3 volts. If you move away from that the problems disappear more than exponentially. Try running 40 MHz if you can.

Good idea. That is usually the first thing I do. I don't know what the default cache mode is in the code right now. Cort and I keep playing with it. I have some running with full copyback enabled.....really nice :-).

I hope the processor upgrade helps, but I have the same problem on the 860T/FADS sometimes as well.

That is the only way. This is why I dislike the FADS boards. I spend way too much time developing tools and no time developing the project software. I used my FADS board to do some simple testing, primarily for developing the UPM programming for the 100 MHz SDRAMs. I was using the ADI connection to a WinBlows machine that crashed more often than the code I was writing on the 860. I got pissed, reprogrammed the Mach part to provide an 8-bit boot interface, soldered a Flash prom socket on the board and bought a ROM simulator to plug into it. This is why my fadsrom file on the server has programs to build S-records and funky format binaries for downloading into it. I then wrote the rom code to load bits from the PCMCIA flash card, and the development path was compile on the PowerBook and blast the ELF image to the PCMCIA card. So, weeks later I was finally able to write the FEC driver I needed for the 860T. Once I got a different 860T board, that FADS thing nearly went to the trash bin.....if it wouldn't have cost so much.....

It is just easier and less expensive to use other types of boards these days.......something that can actually load software minutes after you plug it in.......

    -- Dan

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