..A recent patch note reveals this as it says:
Fix a performance regression on AMD iGPU and dGPU drivers, related to the unintended activation of DMA bounce buffers that regressed game performance if KASLR disturbed things just enough.
Interestingly, this issue, as it turns out, was the consequence of a previous “bad commit” by an Nvidia engineer…
Linus,
Please pull the latest x86/urgent Git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-urgent-2025-04-04
# HEAD: e5f1e8af9c9e151ecd665f6d2e36fb25fec3b110 x86/fred: Fix system hang during S4 resume with FRED enabled
Miscellaneous x86 fixes:
– Fix a performance regression on AMD iGPU and dGPU drivers,
related to the unintended activation of DMA bounce buffers
that regressed game performance if KASLR disturbed things
just enough.– Fix a copy_user_generic() performance regression on certain
older non-FSRM/ERMS CPUs– Fix a Clang build warning due to a semantic merge conflict
the Kunit tree generated with the x86 tree– Fix FRED related system hang during S4 resume
– Remove an unused API
Thanks,
