Re: [PATCH v2 0/8] pdx: introduce a new compression algorithm

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

Hi Roger,

We have an ARM board with the following memory layout:

0x0-0x80000000, 0, 2G
0x800000000,0x880000000, 32GB, 2G
0x50000000000-0x50080000000 5T, 2GB 
0x60000000000-0x60080000000 6T, 2GB 
0x70000000000-0x70080000000 7T, 2GB 

It looks like your PDX series is exactly what we need.  However, I tried
to use it and it doesn't seem to be hooked properly on ARM yet. I spent
some time trying to fix it but I was unsuccessful.

As far as I can tell the following functions need to be adjusted but I
am not sure the list is comprehensive:

xen/arch/arm/include/asm/mmu/mm.h:maddr_to_virt
xen/arch/arm/mmu/mm.c:setup_frametable_mappings
xen/arch/arm/setup.c:init_pdx

Cheers,

Stefano

On Fri, 20 Jun 2025, Roger Pau Monne wrote:
> Hello,
> 
> This series implements a new PDX compression algorithm to cope with the
> spare memory maps found on the Intel Sapphire/Granite Rapids.
> 
> Patches 1 to 7 prepare the existing code to make it easier to introduce
> a new PDX compression, including generalizing the initialization and
> setup functions and adding a unit test for PDX compression.
> 
> Patch 8 introduce the new compression.  The new compression is only
> enabled by default on x86, other architectures are left with their
> previous defaults.
> 
> Thanks, Roger.
> 
> Roger Pau Monne (8):
>   x86/pdx: simplify calculation of domain struct allocation boundary
>   kconfig: turn PDX compression into a choice
>   pdx: provide a unified set of unit functions
>   pdx: introduce command line compression toggle
>   pdx: allow per-arch optimization of PDX conversion helpers
>   test/pdx: add PDX compression unit tests
>   pdx: move some helpers in preparation for new compression
>   pdx: introduce a new compression algorithm based on region offsets
> 
>  CHANGELOG.md                           |   3 +
>  docs/misc/xen-command-line.pandoc      |   9 +
>  tools/tests/Makefile                   |   1 +
>  tools/tests/pdx/.gitignore             |   3 +
>  tools/tests/pdx/Makefile               |  49 ++++
>  tools/tests/pdx/harness.h              |  99 +++++++
>  tools/tests/pdx/test-pdx.c             | 224 +++++++++++++++
>  xen/arch/arm/include/asm/Makefile      |   1 +
>  xen/arch/arm/setup.c                   |  34 +--
>  xen/arch/ppc/include/asm/Makefile      |   1 +
>  xen/arch/riscv/include/asm/Makefile    |   1 +
>  xen/arch/x86/domain.c                  |  40 +--
>  xen/arch/x86/include/asm/cpufeatures.h |   1 +
>  xen/arch/x86/include/asm/pdx.h         |  75 +++++
>  xen/arch/x86/srat.c                    |  30 +-
>  xen/common/Kconfig                     |  37 ++-
>  xen/common/pdx.c                       | 379 ++++++++++++++++++++++---
>  xen/include/asm-generic/pdx.h          |  24 ++
>  xen/include/xen/pdx.h                  | 201 +++++++++----
>  19 files changed, 1056 insertions(+), 156 deletions(-)
>  create mode 100644 tools/tests/pdx/.gitignore
>  create mode 100644 tools/tests/pdx/Makefile
>  create mode 100644 tools/tests/pdx/harness.h
>  create mode 100644 tools/tests/pdx/test-pdx.c
>  create mode 100644 xen/arch/x86/include/asm/pdx.h
>  create mode 100644 xen/include/asm-generic/pdx.h
> 
> -- 
> 2.49.0
>