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

- From: Rob Gardner \<hidden\>
- Date: 2016-03-07 23:15:07 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2016/03/4703439
- Thread: https://ratatoskr.run/sparclinux/2016/03/4699675/t.md

```text
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.

Rob



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