Thread (3 messages) 3 messages, 3 authors, 2000-12-29

Re: 64 bit memory access

From: Dan Malek <hidden>
Date: 2000-12-29 18:09:56

Tim Montgomery wrote:
I need to:
1.) figure out a way to perform a 64bit write via other means
Cache the location.  When you access the space the processor will
do a 64-bit read.  You will have to run in copyback mode then when
done updating the location push the cache line to the device.
Any suggestions/insight would be appreciated.
Using 64-bit only I/O, and FP registers on a 32-bit processor is
an interesting hardware/software hack, but not a very good system
design.

I guess we could write some kernel 64-bit I/O functions that use
an FP register.  This would require disabling interrupts, enabling
the FPU in the kernel, saving a register, doing the I/O, restoring the
register, disabling the FPU, and enabling interrupts.  Not very efficient
when a proper 60x bus implementation that allowed sizing would have
been really fast.........


	-- Dan

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