Eric W. Biederman wrote:
I also think we should default to wp cacheing for the flash region as well.
WP caching?? We should cache it certainly but note that WP caching != Write Protect in the normal sense.
Except for the location the 16->32bit transition this is pretty much what the code currently does. And for our ``normal'' images when we have 2 copies of LinuxBIOS the start up is entirely 32bit.
I was referring to memory type=5, which Intel calls WP (vol 3, 10-23). It is not by default done for the upper 4G regions in linuxbios AFAIK (biosbase=0xffff0000). One has to set XIP_ROM_BASE, XIP_ROM_SIZE, and then an mtrr is set of type 5 for this region, I am pretty sure. It made a big difference in the pcchips787, as I could not use compression otherwise, took too long to decompress, and the watchdog reset kicked off. I have not studied in detail what WP means precisely but I know that others use this type for flash regions.
-Steve