From: Geert U. <ge...@li...> - 2000-10-17 17:03:26
|
On Tue, 17 Oct 2000 fh...@at... wrote: > So, have I got this right? Setup has: > > ncr_cache variable set to 5 > TEMP reg set to 7 > SCRATCHA reg set to aabbff11 > > The script is run and should: > > move ncr_cache (5) in to SCRATCHA > move TEMP (7) in to ncr_cache > move ncr_cache (now 7) back in to TEMP > > That should result in: > > ncr_cache variable set to 7 > TEMP reg set to 7 > SCRATCHA reg set to 5 > > But what you get is: > > ncr_cache variable set to 5 > TEMP reg set to 7 > SCRATCHA reg set to 0 > > So, the only thing that changed is SCRATCHA. That implies 00f40034 really > is the correct address for SCRATCHA as seen by the NCR chip. It also > implies that 082f2058 is NOT the correct address for ncr_cache as seen by > the NCR chip (but but we know the DSP value we are using is correct, as > the script runs). So the `0' in the SCRATCHA register was copied from some unknown location in the address map of the CPU, and not from ncr_cache. Furthermore the `7' was written to that same unknown location. Since it could be read back and stored into the TEMP register (TEMP is still `7', and not garbage), this unknown location must be memory. To find out that unknown location, you can replace the `7' by some easy to find unique value (whatever that may mean, e.g. 0xdeadbeef or 0xdeadcode or 0xfAedbeef (looks like Fredbeef :-)) and search for it in memory after running the DSP script. > So, why is the physical address of the script at the top of memory but the > physical address of ncr_cache down at the bottom of memory? Indeed weird. Perhaps the DSP doesn't have access to all memory. That 64 MB RAM is on the CSPPC and not on your A4000 motherboard, right? > Are virt_to_bus() and virt_to_phys() the same on your platform? I don't think we know that yet... Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@li... In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds |