[ES40-developers] Patch: Misc DMA & System Fixes

[Brian W. <bdw...@in...>]

fixes for the DMA device:
* output wrapped in DEBUG_DMA ifdefs.
* no-op implementation of the different registers

System fixes:
* ignore reads of 0x480 & 0x4c0 (TLBIV, TLBIA).  It looks like
linux (and others) do a read immediately after a write.  Probably to
keep the pchip's addresses in the TLB?

In Linux's arch/alpha/kernel/core_tsunami.c:

184         csr = &pchip->tlbia.csr;
185         if (((start ^ end) & 0xffff0000) == 0)
186                 csr = &pchip->tlbiv.csr;
187 
188         /* For TBIA, it doesn't matter what value we write.  For TBI, 
189            it's the shifted tag bits.  */
190         value = (start & 0xffff0000) >> 12;
191 
192         *csr = value;
193         mb();
194         *csr;

Debugging fixes:
* Require a <RETURN> after a failure call to stop before termination.
This lets the xterm stay alive so I can see what the last message was :)

Brian