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Merge pull request #61 from axel-h/patch-axel-2
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improve wording about about tag
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andresag01 authored Jan 26, 2024
2 parents b2697e2 + 69e17ea commit b87760e
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11 changes: 5 additions & 6 deletions src/cap-description.adoc
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Expand Up @@ -21,18 +21,17 @@ Capabilities contain the software accessible fields described in this section.
[#section_tag]
==== Tag

An additional hardware managed bit added to addressable memory and registers.
It is stored separately and may be referred to as "out of band". It indicates
whether a register or CLEN-aligned memory location contains a valid capability.
If the tag is set, the capability is valid and can be dereferenced (contingent
on checks such as permissions or bounds).
The tag is an additional hardware managed bit added to addressable memory and
registers. It is stored separately and may be referred to as "out of band". It
indicates whether a register or CLEN-aligned memory location contains a valid
capability. If the tag is set, the capability is valid and can be dereferenced
(contingent on checks such as permissions or bounds).

The capability is invalid if the tag is clear. Using an invalid capability to
dereference memory or authorize any operation gives rise to exceptions. All
capabilities derived from invalid capabilities are themselves invalid i.e.
their tags are 0.


All locations in registers or memory able to hold a capability are CLEN+1 bits
wide including the tag bit. Those locations are referred as being _CLEN-bit_ or
_capability_ wide in this specification.
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