iommu: Documentation: rearrange, update kernel-parameters

Add text for some undescribed iommu= parameters (merge, nomerge,
biomerge, panic, nopanic, pt, nopt). Add "usedac" and its description.
Add that iommu=pt is equivalent to iommu.passthrough=1
and that iommu=nopt is equivalent to iommu.passthrough=0.

Move the PPC/POWERNV heading & its option "nobypass" to a separate
area since the current "iommu=" applies only to X86 (according to
its heading).

Unindent the AMD GART IOMMU options heading to make it stand out.
Also add its kconfig symbol name to be explicit about what these
options apply to.

Make sure that the IOMMU options that are listed under AMD Gart
HW IOMMU-specific options are only for that product; i.e., add "force"
there and move "merge", "nomerge", and "panic" to the general IOMMU
options area.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20260528054611.1524937-1-rdunlap@infradead.org>

0 files changed, 0 insertions, 0 deletions