Branch: refs/heads/master
Home: https://github.com/tianocore/edk2
Commit: 7735ed4f8eb3afaf1a97d27a8862f382c387f0bc
https://github.com/tianocore/edk2/commit/7735ed4f8eb3afaf1a97d27a8862f382c387f0bc
Author: ramkumar.s <[email protected]>
Date: 2026-08-23 (Sun, 23 Aug 2026)
Changed paths:
M OvmfPkg/Library/PlatformInitLib/MemDetect.c
Log Message:
-----------
OvmfPkg/PlatformInitLib: Set dynamic MMIO window size to 1/4
Large multi-GPU passthrough configurations can exhaust the current
MMIO window sizing rule (1/8 of guest physical address space),
especially with newer GPUs that have very large BAR requirements and
alignment overhead.
With 46-bit guest physical addressing, the 1/8 rule provides an 8TB
MMIO window. Newer GPUs with 512GB VRAM can exhaust an 8TB window
when passing through up to 8 devices.
Increase the MMIO window size to 1/4 of guest physical address space.
This provides a 16TB MMIO window on a 46-bit setup.
Tested with 8-GPU passthrough (512GB VRAM per GPU). With this
change, all GPUs are visible and functional in the VM; without it,
one GPU was unusable.
Signed-off-by: ramkumar.s <[email protected]>
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