On 11/10/2010 06:18 PM, Scott Duplichan wrote:
] On i945, UMA is done by providing a fixed resource. I don't think any ] other changes were necessary (see src/northbridge/intel/i945/northbridge.c)
I took a look at the i945 code and found the AMD code also adds the exact same fixed resource for the UMA area. What I cannot figure out is how this can reduce the WB DRAM range so that the UMA memory ix excluded.
If I test with 2GB installed and a 256 MB frame buffer, function add_uma_resource is called with the expected arguments: Adding UMA memory area, base=70000000 size=10000000
Later, set_var_mtrr_resource is passed a range of c0000-7fffffff. The existing coreboot code assumes this range has already had the UMA part removed, and adds it back:
// Increase the base range and set up UMA as an UC hole instead var_state.range_sizek += (uma_memory_size>> 10);What logic should deduct the reserved range from the DRAM range before this code runs?
Hmm. The UMA resource should be in high memory. And code should say if UMA high memory resource is used do not allocate c0000. Interesting.....