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From: Alexander Graf <agraf@suse.de>
To: Thomas Huth <thuth@redhat.com>,
	Laurent Vivier <lvivier@redhat.com>,
	kvm@vger.kernel.org, kvm-ppc@vger.kernel.org
Cc: drjones@redhat.com, dgibson@redhat.com, pbonzini@redhat.com
Subject: Re: [PATCH] powerpc: enable 64-bit mode
Date: Tue, 15 Mar 2016 18:44:23 +0000	[thread overview]
Message-ID: <56E85807.5050903@suse.de> (raw)
In-Reply-To: <56E857C2.2020404@redhat.com>



On 15.03.16 19:43, Thomas Huth wrote:
> On 15.03.2016 14:15, Laurent Vivier wrote:
>> When they are started, processors are in 32-bit mode,
>> as we are testing ppc64 processors, enable the 64bit mode
>> on starting.
>>
>> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
>> ---
>>  powerpc/cstart64.S | 9 +++++++++
>>  1 file changed, 9 insertions(+)
>>
>> diff --git a/powerpc/cstart64.S b/powerpc/cstart64.S
>> index c87e3d6..634b854 100644
>> --- a/powerpc/cstart64.S
>> +++ b/powerpc/cstart64.S
>> @@ -18,6 +18,15 @@
>>  .globl start
>>  start:
>>  	FIXUP_ENDIAN
>> +
>> +	/* enable 64-bit mode */
>> +	mfmsr	r11
>> +	li	r12,-1
>> +	rldicr	r12,r12,0,0
> 
> Nice idea to set the highest bit, I didn't know that one yet :-)
> 
>> +	or	r11,r11,r12
>> +	mtmsrd	r11
>> +	isync
> 
> Looks good!
> 
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> 
> 
> PS: As far as I can see, the C code has already been compiled for 64
> bits ... how did that work if it has been run in 32-bit mode so far??

And why would we enter a 64bit CPU without MSR_SF set?


Alex

  reply	other threads:[~2016-03-15 18:44 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-15 13:15 [PATCH] powerpc: enable 64-bit mode Laurent Vivier
2016-03-15 13:43 ` Laurent Vivier
2016-03-15 18:43 ` Thomas Huth
2016-03-15 18:44   ` Alexander Graf [this message]
2016-03-15 19:10     ` Thomas Huth
2016-03-15 20:12     ` Laurent Vivier
2016-03-16  9:45     ` Laurent Vivier

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