On Wed, 4 Sep 2002, Dominic Sweetman wrote: > Well, next time, get your board designers to think before they map... > > It's generally better to map some DRAM low (for boot ROMs and other > stupid programs you don't want to make big-address aware), then remap > the whole DRAM to some very high address for Linux. Much better than > forcing you to use the TLB (or XKPHYS, if you've a 64-bit CPU) to get > at I/O. Hmm, what's the deal? Other processors always use MMU to access iomem... > Bear in mind that there *isn't a 64-bit mode*. Privileged code (which > is everything except Linux applications) can always run 64-bit > instructions; all addresses are 64-bits really, it's just the > sign-extension of the registers which makes you think you've got > 32-bit pointers. Usually a 64-bit CPU can access XKPHYS any time > it can access I/O registers. Well, it's mostly a programming convention. Without going into details, arch/mips is the 32-bit mode and arch/mips64 is the 64-bit one. The usual approximation is the state of cp0.kx, even though 64-bit operations do indeed work when ~cp0.kx. -- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available +
