CPUTYPE for VIA C7-M

[Deluted]

Hello, I'm planning to install FreeBSD 7.0 on a HP 2133 Mini-Note. However, I have tried to find the CPUTYPE to use in make.conf and I cannot find a concrete answer.

The closest ones in make.conf seem to be c3 or c3-m but I'm not sure whether that will work on a C7-M type. The Safe CFLAGS on Gentoo-Wiki says "i686" but I'm not sure whether that is a valid CPUTYPE. Searching this forum turns up "native" as an alternative, but there are reports of it not working properly in FreeBSD 7.0 due to some bug.

Any ideas?

[graudeejs]

Gentoo != FreeBSD
Do nothing, just skip editing make.conf....

[Deluted]

I know FreeBSD is not the same as Gentoo, but I came across a post on checking out the Safe CFLAGS page here so I'd thought it could give me a clue on what to use.

So, you think I should just leave make.conf alone? Would it make my programs slower than if CPUTYPE was set, or would the difference be minuscule?

[graudeejs]

you won't probably notice significant difference.

Another thing on FreeBSD, you NEVER edit Cflags, they break things...



Show output of

$ dmesg | grep cpu

[mdh]

The gcc man page has a list of CPUTYPE options, which are -march flags to gcc.

I always set my CPUTYPE, and it works great. Since I compile everything locally, I come up with a fairly optimized system overall, and I'm very happy with the performance of it.

[Deluted]

$ dmesg | grep cpu
cpu0: <ACPI CPU> on acpi0
est0: <Enhanced SpeedStep Frequency Control> on cpu0
p4tcc0: <CPU Frequency Thermal Control> on cpu0

I have also looked at the man page for gcc and found generic, native, i686, c3 and c3-2 under the -mtune=cpu-type section. Are any of those right?

[graudeejs]

ups, my mistake, i mean
show output of

$ dmesg | grep CPU

[TerryP]

Originally Posted by Deluted

So, you think I should just leave make.conf alone? Would it make my programs slower than if CPUTYPE was set, or would the difference be minuscule?

If you really want to notice a difference, try FreeBSD amd64 with a pair of high end server CPUs and a crap load of RAM.

[phoenix]

The list of known CPUTYPEs and what CPUs they can be used for is listed in /usr/share/examples/etc/make.conf

For FreeBSD 7.0, there's nothing listed specifically for the VIA C7.

[mdh]

Any or all of i686, c3, and c3-2 could be correct for your chip. I can't say which one is correct. If in doubt, use i686 as that will most certainly produce sane, compatible code. One of c3 or c3-2 will likely produce more optimized code, but I have no way to know which would work for you. Study the gcc man page and what it says about it of those options, then compare that data to what you know about the CPU you have.

As someone who knows something about VIA chips, do you happen to know the core model of your chip? I am not as familiar with C7's. One other thing you'll want to remember to do is to enable the Padlock functionality in your kernel by enabling it in your kernel config, or running kldload padlock.

[mdh]

Originally Posted by phoenix

For FreeBSD 7.0, there's nothing listed specifically for the VIA C7.

This is because there aren't signifigant enough differences between what VIA sells as C3 and what they sell as C7, architecturally, therefore GCC doesn't have a seperate optimization profile for those sold as C7s. It's marketing terminology more than a genuine difference in technology. That said, there are some very signifigant differences between some early (Cyrix design based) C3 chips, and the latter chips which forked very far from the early Cyrix designs and implemented some really cool stuff like the Padlock RNG and crypto instruction sets.

[robbak]

Originally Posted by mdh

That said, there are some very signifigant differences between some early (Cyrix design based) C3 chips, and the latter chips which forked very far from the early Cyrix designs and implemented some really cool stuff like the Padlock RNG and crypto instruction sets.

That sounds to me like c3-2 is the best one.
So, cpu I686_CPU in your kernel config file, and CPUTYPE=c3-2 in make.conf

And leave CFLAGS and COPTFLAGS alone!

[Deluted]

$ dmesg | grep CPU
CPU: VIA/IDT Unknown (1596.01-MHz 686-class CPU)
cpu0: <ACPI CPU> on acpi0
p4tcc0: <CPU Frequency Thermal Control> on cpu0

At the moment, I'm leaning towards i686 for CPUTYPE considering the information above. Any last suggestions?

[graudeejs]

# The CPUTYPE variable controls which processor should be targeted for
# generated code.  This controls processor-specific optimizations in
# certain code (currently only OpenSSL) as well as modifying the value
# of CFLAGS to contain the appropriate optimization directive to gcc.
# The automatic setting of CFLAGS may be overridden using the
# NO_CPU_CFLAGS variable below.
# Currently the following CPU types are recognized:
#   Intel x86 architecture:
#       (AMD CPUs)      opteron athlon64 athlon-mp athlon-xp athlon-4
#                       athlon-tbird athlon k8 k6-3 k6-2 k6 k5
#       (Intel CPUs)    core2 core nocona pentium4m pentium4 prescott
#                       pentium3m pentium3 pentium-m pentium2
#                       pentiumpro pentium-mmx pentium i486 i386
#       (Via CPUs)      c3 c3-2
#   Alpha/AXP architecture: ev67 ev6 pca56 ev56 ev5 ev45 ev4
#   AMD64 architecture: opteron, athlon64, nocona, prescott, core2
#   Intel ia64 architecture: itanium2, itanium

CPUTYPE=i686 ain't supported by make.conf
i686 is something like Pentium 2 (i'f i'mm correct, hold on i'll check), but who know's how compitable via's chip is
just leave it alone (or use i486 or c3 or c3-2)

[graudeejs]

yup, i686 was introduced with name Pentium Pro and Pentium 2, the i686 still lives on.... in nowadays chips

and pentium 1 was i586

[Deluted]

I've looked at a normal dmesg and found this:

CPU: VIA/IDT Unknown (1596.01-MHz 686-class CPU)
  Origin = "CentaurHauls"  Id = 0x6d0  Stepping = 0
  Features=0xa7c9bbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,
CMOV,PAT,CLFLUSH,ACPI,MMX,FXSR,SSE,SSE2,TM,PBE>
Features2=0x4181<SSE3,EST,TM2,xTPR>

I then found this in bsd.cpu.mk:

.  elif ${CPUTYPE} == "c3"
MACHINE_CPU = 3dnow mmx i586 i486 i386
.  elif ${CPUTYPE} == "c3-2"
MACHINE_CPU = sse mmx i586 i486 i386

Since my CPU apparently supports SSE and c3-2 has it included, I'm going to try using c3-2 as my CPUTYPE. If it all goes wrong, then I'll revert back to a blank configuration.

I have also left the FLAGS stuff alone.

Thanks to all of you for helping me!

[Carpetsmoker]

Another thing on FreeBSD, you NEVER edit Cflags, they break things...

Only if you don't know what you're doing.

[graudeejs]

Originally Posted by Carpetsmoker

Only if you don't know what you're doing.

i know..., that's why i always say to leave them alone

[TerryP]

Originally Posted by Carpetsmoker

Only if you don't know what you're doing.

In my opinion, that rules out most people who lack commit access to the FreeBSD src ;-)

[mdh]

Originally Posted by robbak

That sounds to me like c3-2 is the best one.
So, cpu I686_CPU in your kernel config file, and CPUTYPE=c3-2 in make.conf

And leave CFLAGS and COPTFLAGS alone!

No. Use CPUTYPE?=, not CPUTYPE=. This allows the build system to override it if necessary.