# [solved] Sempron kernel configuration

## tbart

Hello!

As there's a lot of confusion and little information on the net:

What is the correct kernel configuration for AMD Sempron Processors?

powernow-k8 seems to be right, but what about the "processor family"?

is it K8 or K7 ?

the kernel help for K8 seems 64Bit oriented, but i am sure sempron does not understand 64Bit instructions, but it needs powernow-k8, so processor family k7 seems wrong...

confusing...

could anyone please help?

TIA,

tbartLast edited by tbart on Thu Mar 30, 2006 11:56 am; edited 1 time in total

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## NeddySeagoon

tbart,

Sempron means a K7 or K8 with half the cache chopped out.

They are avaiable in K7 or K8 processor versions

Have you got a 32 bit Sempron, which is a cut down Athlon

or a 64 bit Sempron which is a cut down AMD64?

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## tbart

difficult to say... it's in a friend's notebook... i know the difference is the socket... i don't want to open it ;->

i know right know that it has sse2 (what my athlon XP-m/K7 here does not have) and that powernow-k8 says it detects Hammer/Opteron/... -> seems like K8?

(but fails somewhere at the "vidtrans" thing at the end of the initialisation - this is supposed to be my next question:

how to powernow on a sempron?

)

i will edit this post as soon as i have access to the machine (will post some cat /proc/cpuinfo or sth. i find important)

BTW: i heard even the cut-back AMD64 version lacks 64Bit instructions - so there seem to be more cut-backs than simply L2 cache...

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## NeddySeagoon

tbart,

 *Quote:*   

> Hammer/Opteron/.

 means its a AMD64 CPU.

There will be no socket in a notebook. The CPU will be soldered in to save space, just as well you didn't look.

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## MerlinTheWizard

 *NeddySeagoon wrote:*   

> 
> 
> There will be no socket in a notebook. The CPU will be soldered in to save space, 

 

I don't think so...  :Rolling Eyes: 

Anyway, if this is a K8 Sempron, then this is the 3100+, as far as I know, this is the only Sempron that is a stripped down AMD 64. All other Sempron's are socket A, good old Athlon architecture.

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## tbart

Sorry for the delay...

here comes my cpuinfo:

```

LiesiGentooBox root # cat /proc/cpuinfo

processor       : 0

vendor_id       : AuthenticAMD

cpu family      : 15

model           : 8

model name      : Mobile AMD Sempron(tm) Processor 2800+

stepping        : 2

cpu MHz         : 1601.762

cache size      : 256 KB

fdiv_bug        : no

hlt_bug         : no

f00f_bug        : no

coma_bug        : no

fpu             : yes

fpu_exception   : yes

cpuid level     : 1

wp              : yes

flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx mmxext 3dnowext 3dnow

bogomips        : 3153.92

```

thanks for your advises: as you see, everyone seems to know different things.

if it is just an athlon XP with a different name and half the cache - as lots of people say - why does powernow-k7 definitely NOT work, that is: not find a CPU capable of it, and why does it have sse2?

(and why does powernow-k8 fail powersaving   :Laughing:  ):

```

LiesiGentooBox root # dmesg

powernow-k8: Found 1 AMD Athlon 64 / Opteron processors (version 1.00.09b)

powernow-k8:    0 : fid 0x8 (1600 MHz), vid 0x6 (1400 mV)

powernow-k8:    1 : fid 0x0 (800 MHz), vid 0x18 (950 mV)

powernow-k8: cpu_init done, current fid 0x8, vid 0x4

powernow-k8: vid trans failed, vid 0x3, curr 0x4

powernow-k8: transition frequency failed

```

it seems like there are two fixed states an AMD64/Opteron can do (for which powernow-k8 is written) but after determining the actual state, powernow-k8 recognizes that the CPU is in a not-defined state....

or am i wrong in thinking this?

btw: this is what it seems to be like when it's working (on an AMD64)

it finds a valid state

 *Quote:*   

> 
> 
> powernow-k8: Found 1 AMD Athlon 64 / Opteron processor(version 1.00.09b) 
> 
> powernow-k8:    0 : fid 0xc (2000 MHz), vid 0x2 (1500 mV) 
> ...

 

i guess i will have a look at the sources and play around a bit - or is it dangerous? voltage-wise?

hope someone can help me...

or i'm gonna be back with a self-made solution   :Smile: 

tbart

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## MerlinTheWizard

Ok, well well.

I was slightly misleaded. What I said was true for the "desktop" line of Sempron's, but not for the "mobile" Sempron's. Go figure what the marketing reasoning behind all this really is...

Anyway: all Mobile Sempron processors seem to be based on the Mobile Athlon 64 architecture, this is why they are "somehow" seen as K8. They don't have any of the 64-bit extensions, though, and less cache.

All that being said, these are not fully supported by the linux kernel. I know some bugs have been fixed in kernel 2.6.10. What kernel version are you using?

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## tbart

2.6.9-gentoo-r12, going to upgrade to 2.6.10 as soon as they get unmasked...

so: what do i learn: choose K8 under processor family or better K7 (I'm now with K7 and everything seems to work well, but maybe there is more to get ? )

and, if i do, do i have to recompile everything, or at least system not world?

BTW: powernow works now. maybe just an acer issue:

http://kernel.org/pub/linux/kernel/people/brodo/patches/2.6.10-rc2/cpufreq-09-powernow-k8-acer-fix

but i guess this will work for all the people having this problem (if someone reads this: give it a try)

tbart

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## Sarlock

Hi, I'm having trouble configuring my kernel from scratch with the AMD Sempron 2500+ processor, when I used Genkernel it said it was in the K6 family, but I somehow get the feeling that it's not correct.  I didn't like how Genkernel configured everything so I wiped and have started again from scratch.  It's pretty much a rundown Athlon XP, so I'm wondering if I should set K6 or K7 as the family?

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## MerlinTheWizard

As far as I know, it's the K7 family.

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## Sarlock

Thank you.  I will try this once more.  :Smile: 

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## yottabit

K7 is correct for Sempron on Socket A.

(Though I've read that the Sempron is simply an Athlon 64 with less cache and 64-bit instructions disabled, so maybe K8 is worth a try? But it's not really a full K8, so...)

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## MerlinTheWizard

 *yottabit wrote:*   

> K7 is correct for Sempron on Socket A.
> 
> (Though I've read that the Sempron is simply an Athlon 64 with less cache and 64-bit instructions disabled, so maybe K8 is worth a try? But it's not really a full K8, so...)

 

Nope, as I said, it's only true for the Sempron "mobile". The "desktop" line of Sempron's are just plain Athlon XP, except some of them (like the 3100+?) which are what you describe (stripped-down Athlon 64 on socket 754).

If it's on a Socket A, you can rest assured it's a K7!

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