mirror of
https://github.com/xen-project/xen.git
synced 2026-10-28 10:11:27 +01:00
Oleksii Kurochko
2addc9f051
H provides additional instructions and CSRs that control the new stage of
address translation and support hosting a guest OS in virtual S-mode
(VS-mode).
According to the Unprivileged Architecture (version 20240411) specification:
```
Table 74 summarizes the standardized extension names. The table also defines
the canonical order in which extension names must appear in the name string,
with top-to-bottom in table indicating first-to-last in the name string, e.g.,
RV32IMACV is legal, whereas RV32IMAVC is not.
```
According to Table 74, the h extension is placed last in the one-letter
extensions name part of the ISA string.
`h` is a standalone extension based on the patch [1] but it wasn't so
before.
As the minimal supported GCC version to build Xen for RISC-V is 12.2.0,
and for that version, h is still considered a prefix for the hypervisor
extension but the name of hypervisor extension must be more then 1 letter
extension, a workaround ( with using `hh` as an H extension name ) is
implemented as otherwise the following compilation error will occur:
error: '-march=rv64gc_h_zbb_zihintpause': name of hypervisor extension
must be more than 1 letter
After GCC version 13.1.0, the commit [1] introducing H extension support
allows us to drop the workaround with `hh` as hypervisor extension name
and use only one h in -march.
[1] https://github.com/gcc-mirror/gcc/commit/0cd11d301013af50a3fae0694c909952e94e20d5#diff-d6f7db0db31bfb339b01bec450f1b905381eb4730cc5ab2b2794971e34647d64R148
Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Sphinx documentation:
All source rendered by Sphinx is licensed under CC-BY-4.0.
You are free to:
Share:
Copy and redistribute the material in any medium or format.
Adapt:
Remix, transform, and build upon the material for any purpose, even
commercially.
Under the following terms:
Attribution:
You must give appropriate credit, provide a link to the license, and
indicate if changes were made. You may do so in any reasonable manner, but
not in any way that suggests the licensor endorses you or your use.
No additional restrictions:
You may not apply legal terms or technological measures that legally
restrict others from doing anything the license permits.
See https://creativecommons.org/licenses/by/4.0/ for full details.
This includes:
* All ReStructured Text files: docs/*/*.rst
* The Sphinx configuration file: docs/conf.py
* Content in Sphinx-exclusive subdirs: docs/*-guide/*
Other documentation:
There are a variety of text documents in various formats. These, given no
explicit license guidance, fall under Xen's default GPL-2.0 license.