ron minnich rminnich@lanl.gov writes:
On Tue, 16 Sep 2003, Stefan Reinauer wrote:
This could be done using the Opterons PAE feature. Currently I see a tradeoff between LinuxBIOS image size and the design conflict when going away from 16bit firmware on 32bit systems while staying with 32bit on a 64bit platform.
this won't last very long here. 36 bits only gets us to 64 GB -- too small.
PAE is really has 64bit addresses in the page tables. Intel implements 36bits physical and AMD 40bits of physical address space.
LinuxBIOS has run in 64-bit mode on a 64-bit platform -- the alpha. I see no real issue with going to 64-bit opteron mode.
Neither do I. I have memory initialization working for all 64bits in 32bit physical mode, so it isn't needed at the moment. But there is a noticeable performance hit.
Any dynamic page table based solution though needs to move out of romcc compiled code, and into the normal part of LinuxBIOS where we already have memory initialized. That's not a bad idea anyway given how slow it is to do memory writes over hypertransport before the link speed is configured up.
rno
Eric