Subject: Re: [PATCH -V3 2/3] powerpc: Update kernel VSID range

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Wed, 13 Mar 2013 14:47:06 +0530

Paul Mackerras <[email-masked]> writes:

> On Tue, Mar 12, 2013 at 05:38:50PM +0530, Aneesh Kumar K.V wrote:
>> From: "Aneesh Kumar K.V" <[email-masked]>
>> 
>> This patch change the kernel VSID range so that we limit VSID_BITS to 37.
>> This enables us to support 64TB with 65 bit VA (37+28). Without this patch
>> we have boot hangs on platforms that only support 65 bit VA.
>> 
>> With this patch we now have proto vsid generated as below:
>> 
>> We first generate a 37-bit "proto-VSID". Proto-VSIDs are generated
>> from mmu context id and effective segment id of the address.
>> 
>> For user processes max context id is limited to ((1ul << 19) - 5)
>> for kernel space, we use the top 4 context ids to map address as below
>> 0x7fffc -  [ 0xc000000000000000 - 0xc0003fffffffffff ]
>> 0x7fffd -  [ 0xd000000000000000 - 0xd0003fffffffffff ]
>> 0x7fffe -  [ 0xe000000000000000 - 0xe0003fffffffffff ]
>> 0x7ffff -  [ 0xf000000000000000 - 0xf0003fffffffffff ]
>> 
>> Signed-off-by: Aneesh Kumar K.V <[email-masked]>
>
> Mostly looks OK, and it could go in as is, so
>
> Acked-by: Paul Mackerras <[email-masked]>
>
> Some minor comments below...
>
>> + * For user processes max context id is limited to ((1ul << 19) - 6)
>
> should be ((1ul << 19) - 5)

I update the commit message but missed updating this.  

Ben,

Let me know if you want me to send V4 to take care of these review
feedbacks.

-aneesh