linux-kernel - Re: Linux 2.6.38.4 : regression due to x86 AMD ARAT feature

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Message-ID: <4DB47211.90901@dynato-kyma.net>
Date:	Sun, 24 Apr 2011 20:55:13 +0200
From:	Jörg-Volker Peetz <peetz@...ato-kyma.net>
To:	Borislav Petkov <bp@...en8.de>,
	Jörg-Volker Peetz <jvpeetz@....de>,
	linux-kernel@...r.kernel.org,
	Boris Ostrovsky <boris.ostrovsky@....com>,
	Andreas Herrmann <andreas.herrmann3@....com>,
	Borislav Petkov <borislav.petkov@....com>
Subject: Re: Linux 2.6.38.4 : regression due to x86 AMD ARAT feature

Borislav Petkov wrote, on 04/24/11 20:20:
> On Sun, Apr 24, 2011 at 10:06:36AM +0200, Jörg-Volker Peetz wrote:
>> With 2.6.38.4 the clock slows down and the affected laptop sometimes, e.g. for
>> the output of "ps axuw" to appear, needs an input from the keyboard or the
>> touchpad. Please find attached the kernel config file and the output of dmesg.
>>
>> Commenting out the the lines
>>
>> 	if (c->x86 >= 0xf && !cpu_has_amd_erratum(amd_erratum_400))
>> 		set_cpu_cap(c, X86_FEATURE_ARAT);
>>
>> in arch/x86/kernel/cpu/amd.c makes this laptop work as before with kernel
>> 2.6.38.3. I think these lines came with commit
>> d7b7f0c401303dd7eafcff11752fe74d3b75c766.
> 
> Hmm, interesting.
> 
> Can you send also /proc/cpuinfo please?
> 
> Looks like your CPU is a single core K8 revE or something but we'd need
> the exact family info.
> 
> Thanks.
> 

Here it comes:


processor	: 0
vendor_id	: AuthenticAMD
cpu family	: 15
model		: 36
model name	: AMD Turion(tm) 64 Mobile Technology MT-40
stepping	: 2
cpu MHz		: 800.000
cache size	: 1024 KB
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 fxsr_opt lm 3dnowext 3dnow rep_good
nopl pni lahf_lm
bogomips	: 1592.98
TLB size	: 1024 4K pages
clflush size	: 64
cache_alignment	: 64
address sizes	: 40 bits physical, 48 bits virtual
power management: ts fid vid ttp tm stc

This is a nice mobile processor and i thought it was sold quite a lot.
-- 
Best regards,
Jörg-Volker.
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