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The PAPR "Nestedv2" guest API introduces the concept of a Guest State Buffer for communication about L2 guests between L1 and L0 hosts. In the new API, the L0 manages the L2 on behalf of the L1. This means that if the L1 needs to change L2 state (e.g. GPRs, SPRs, partition table...), it must request the L0 perform the modification. If the nested host needs to read L2 state likewise this request must go through the L0. The Guest State Buffer is a Type-Length-Value style data format defined in the PAPR which assigns all relevant partition state a unique identity. Unlike a typical TLV format the length is redundant as the length of each identity is fixed but is included for checking correctness. A guest state buffer consists of an element count followed by a stream of elements, where elements are composed of an ID number, data length, then the data: Header: <---4 bytes---> +----------------+----- | Element Count | Elements... +----------------+----- Element: <----2 bytes---> <-2 bytes-> <-Length bytes-> +----------------+-----------+----------------+ | Guest State ID | Length | Data | +----------------+-----------+----------------+ Guest State IDs have other attributes defined in the PAPR such as whether they are per thread or per guest, or read-only. Introduce a library for using guest state buffers. This includes support for actions such as creating buffers, adding elements to buffers, reading the value of elements and parsing buffers. This will be used later by the nestedv2 guest support. Signed-off-by: Jordan Niethe <jniethe5@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230914030600.16993-9-jniethe5@gmail.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.