Greetings!
If I call the dflush() function in cpu/ppc4xx/start.S on a PPC440EPx as part of initializing SDRAM, I later get the error
The value of DVLIM special register is incorrect: 0x00000000
from spr_post_test(). I can make the spr_post_test() error message go away by applying the patch
--- a/cpu/ppc4xx/start.S +++ b/cpu/ppc4xx/start.S @@ -1711,6 +1711,7 @@ trap_reloc: rlwinm r8,r9,0,15,13 rlwinm r8,r8,0,17,15 mtmsr r8 + mfspr r8,dvlim addi r3,r0,0x0000 mtspr dvlim,r3 mfspr r3,ivpr @@ -1725,6 +1726,7 @@ trap_reloc: ..ag: dcbf r0,r3 addi r3,r3,-32 bdnz ..ag + mtspr dvlim,r8 sync mtmsr r9 blr
The routine dflush() zeros DVLIM but does not save and restore the original value. Is this the intended behavior? The patch I tried seems safe, although I couldn't easily find the gcc function calling conventions for PowerPC. (Does anyone have a pointer to these?)
-- Best regards, Larry Johnson lrj@acm.org