Re: Why does FBSD always assume it's on an 8080 CPU?

Chris H. wrote:
...or when will FreeBSD support Pentium features?

I want to apologize in advance if this should be on the kern@
But it seemed apropriate for this list too and I'm already on it.
I've noticed building kernels, that since v. >= 5 that during
the phase 2/3 all the lines echoed to the screen contain:
-mno-mmx -mno-3dnow -mno-sse -mno-sse2 ...
As Pentium have been the "norm" for many years now, why aren't
these /assumed/? I'm building on several SMP PIII's and a build
is in process now on a PIV Athalon running 6.2 the source and
ports tree were cvsupped 01-25 @02:03:00 -0800. Yet this
current kernel build is echoing these same -mno- lines. I have
machine i386
cpu I686_CPU
device apic
uncommented and I386_CPU, I486_CPU & I586_CPU commented. I have
grepped the /src/sys/conf/NOTES as well as the /src/sys/i386/conf/NOTES
Yet the only case I find relating to this is on line: 130 in:
/src/sys/i386/conf/NOTES which reads:
# CPU_ENABLE_SSE enables SSE/MMX2 instructions support. This is default
# on I686_CPU and above.
Default? hmmm... not as far as I can tell. Anyway, I would *greatly*
appreciate any insight on this issue. Do I need to pollute my make.conf
file to achive a Pentium kernel?

Thank you very much for all your time and consideration.

--Chris


Context switching.

We already preserve the "core" CPU state and the FPU state between context switches. Adding MMX into the mix means preserving an MMX state (since it can clobber the FPU state) and so forth.

jmc

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