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Differential D56846

bhyve: enlarge 64-bit PCI MMIO hole to 1 TiB
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Authored by tsoome on May 6 2026, 10:23 AM.
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bcran
bnovkov
imp
rgrimes

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bhyve
Summary

Default 32 GiB hole is insufficient for modern GPUs whose BAR1 (HBM
aperture) is 128 GiB each. Four H100 SXM5 GPUs need ~512 GiB of
prefetchable 64-bit PCI MMIO. Bump to 1 TiB for headroom, covering
future hardware like H200 (192 GiB/GPU).

Assisted-By: Claude Opus 4.7 (1M context)

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Repository
rG FreeBSD src repository
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Build Status
Buildable 72843
Build 69726: arc lint + arc unit

Event Timeline

tsoome created this revision.May 6 2026, 10:23 AM
Herald added a reviewer: bhyve. · View Herald TranscriptMay 6 2026, 10:23 AM
Herald added subscribers: bcran, rgrimes, imp. · View Herald Transcript
tsoome requested review of this revision.May 6 2026, 10:23 AM
Harbormaster completed remote builds in B72843: Diff 177293.May 6 2026, 10:23 AM
bnovkov added a subscriber: bnovkov.May 6 2026, 2:16 PM

Was this change motivated by this comment in PR290920 and have you tested this patch somehow yet?
If not, I think that commenter would be more than willing to test it.

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usr.sbin/
bhyve/
8 lines

Diff 177293

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usr.sbin/bhyve/pci_emul.c

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