# Re: \[PATCH v2\] sparc64: Add support for Application Data Integrity (ADI)

- From: Khalid Aziz \<hidden\>
- Date: 2016-03-07 23:28:54 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2016/03/4703492
- Thread: https://ratatoskr.run/sparclinux/2016/03/4699675/t.md

```text
On 03/07/2016 04:12 PM, Rob Gardner wrote:
> On 03/07/2016 01:33 PM, Khalid Aziz wrote:
>>
>> That is a possibility but limited in scope. An address range covered
>> by a single TTE can have large number of tags. Version tags are set on
>> cacheline. In extreme case, one could set a tag for each set of
>> 64-bytes in a page. Also tags are set completely in userspace and no
>> transition occurs to kernel space, so kernel has no idea of what tags
>> have been set.
>
>    ...
>> I have not found a way to query the MMU on tags.
>>
>
> To query the tag for a cache line, you just read it back with ldxa and
> ASI_MCD_PRIMARY (ie, asi 0x90), basically the same way you stored the
> tag in the first place.
>

Thanks, Rob. I just saw it while reading through the manual.

--
Khalid

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```