The 2026-09-11 trade bought a vendor-claimed 13-16% prefill figure that was
never measured here; the 2026-10-18 research (same decision record) shows what
identity mode actually costs the iGPU is the 1:1 page walk plus ATS/PRI/PASID/
GCR3 -- worth 2-4% on this silicon class, and removable outright by AMD PerfOpt
when the distro ships Linux 7.4. Meanwhile pt is what err=-19 asks for: the
XDNA2 NPU binds its own IOPT_TYPE_SVA domain and only needs the IOMMU enabled.
Measured off-vs-pt prefill arms follow in the docs commit; frank-archon
(Dankserver) is untouched.
Frank
1b373f3559