Subject: Re: 64 bit memory access

From: Dan Malek <[email-masked]>
Date: Fri, 29 Dec 2000 13:09:56 -0500

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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