Anybody, I ran into a peculiar issue, though it could be user error.
I am using U-boot to configure up the SDRAM and SRAM in our system before we launch Linux. We have 32 Mb of SDRAM and 2 MB of SRAM in the system. If I leave the SRAM mapped at higher addresses 0x10000000 and SDRAM at 0x00000000, like U-boot defaults to Linux works great. However, my goal is to map SRAM <8ns speeds> down to the address 0x00000000, to map the vector table, so I can achieve a very fast interrupt response time. I hacked U-boot a little bit to remap these addresses, after all the init code was finished. U-boot relocates itself to higher memory, i.e. the last 2MB's of SDRAM and all is well within U-boot. I ran a 14 hour test on the memory area to proof it. Now we have 0x02200000 <34M> memory size being reported to Linux, in the bd->memsize. However, now Linux crashes randomly all over the place, mostly sig11's task: swapper. I know this is not an issue with SDRAM stability, and I can't imagine SRAM having problems seeing as its 8ns capable and we're running at 15ns at the moment (66mhz). Linux reports BAT mappings as BAT2=32Mb, BAT3=2MB when all 34 Megs are presented via U-boot. Does anyone have any idea what would cause this instability? Physically all memory seems to be great if used by itself. I know very little about how Linux manages its pages, BATS, TBLs, etc... Are the limits on odd memory sizes? Or certain configurations that it expects to see? Thanks in advance. -Russell McGuire
