Xen Project Releases Version 4.20

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

Hello everyone,

It's with great pleasure that I announce our 4.20 PR release.

I want to thank the whole community for their efforts in getting this
release published!

*Please find the PR article attached here
<https://www.linuxfoundation.org/press/xen-project-announces-xen-420-release
>*

Please find the tarball and its signature at:
   https://downloads.xenproject.org/release/xen/4.20.0/

You can also check out the tag in xen.git:
   git://xenbits.xen.org/xen.git RELEASE-4.20.0

Git checkout and build instructions can be found at:
   https://wiki.xenproject.org/wiki/Xen_Project_4.20_Release_Notes#Build_Requirements

Release notes can be found at:
   https://wiki.xenproject.org/wiki/Xen_Project_4.20_Release_Notes

A summary for 4.20 release documents can be found at:
   https://wiki.xenproject.org/wiki/Category:Xen_4.20

*Some notable features:*
  - *Security Enhancements:*
    - During the 4.20 development window, 8 new Xen Security Advisories (XSAs) were published.
    - Expanded MISRA C compliance: Integrated ECLAIR MISRA C scanner in GitLab CI, enforcing 90
      rules with zero unjustified violations.
    - Enabled UBSAN (Undefined Behaviour Sanitiser) by default for x86, Arm64, RISC-V and PowerPC
      in GitLab CI.
    - Integrated two of our existing fuzzing harnesses into OSSFuzz.
  
 - *Arm*
    - Support for LLC (Last Level Cache) coloring for performance optimizations.
    - Experimental support for Armv8-R.
    - Support for NXP S32G3 Processors Family and LINFlexD UART driver.
    - To enable Xen towards safety certification, 43 requirements have been added. 

 - *x86 Architecture:*
    - On Intel CPUs, support the Paging-Write Feature.
    - AMD Zen 5 CPU support, including mitigation for SRSO speculative vulnerability.
    - Improve Xen ability to boot (and reboot) using the default configuration on possibly
      quirky EFI firmware.
    - Switched the xAPIC flat driver to use physical destination mode for external interrupts instead
      of logical destination mode. 
    - Remove support for running on Xeon Phi processors.
    - There has been a substantial overhaul to the way in which boot module handling works (part of the
      Hyperlaunch work in progress), and a substantial overhaul to how the 32bit early boot code is built
      and linked (part of the UEFI SecureBoot work in progress).


 - *Other updates:*
   - Fixes in the blkif protocol specification for non-512b sector sizes.
   - Security and performance enhancements: The domain builder in libxenguest no longer un-gzips
     secondary modules, leaving it to the guest kernel.
   - Continued to improve the common/arch code split, including improved bit-operation helpers for bit
     scanning and hamming weight.

Aside from the updates mentioned, I would also like to note that we are
still continue working on the PPC and RISC-V ports.

Best regards,
 Oleksii

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