iucode_tool(8): document changes to --scan-system

Document the new --scan-system behavior as well as its modes of
operation in the manpage.
parent b97d0909
......@@ -201,7 +201,7 @@ The special notation \fI\-s!\fP (with no \fIsignature\fP parameter) instructs
the non\-negated form of \fI\-s\fP, or using \fI\-\-scan\-system\fP).
.BR "\-S" ", " "\-\-scan\-system"
.BR "\-S" ", " "\-\-scan\-system" "[=\fImode\fP]"
Select microcodes by scanning online processors on this system for their
......@@ -210,10 +210,26 @@ option to select more microcodes. The microcodes selected by
\fI\-\-scan\-system\fP can also be deselected by a later \fI\-s\ !signature\fP
Should the signature scan fail, the program will print a warning to the user
and continue as if \fI\-\-scan\-system\fP had not been specified. This is a
fail-safe condition when \fBiucode_tool\fP is used to install microcode updates
for the next boot.
The optional \fImode\fP argument (accepted only by the long version of the
option) selects the strategy used to scan processors:
.IP "\fB0\fP or \fBauto\fP"
Currently the same as \fBfast\fP, but this might change in future versions if
Intel ever deploys multi-signature systems that go beyond mixed-stepping. This
is the default mode of operation, for backwards compatibility
with previous versions of \fBiucode_tool\fP.
.IP "\fB1\fP or \fBfast\fP"
Uses the cpuid instruction to detect the signature of the processor
\fBiucode_tool\fP is running on, and selects all steppings for that processor's
type, family and model. Supports mixed-stepping systems.
.IP "\fB2\fP or \fBexact\fP"
Uses kernel drivers to scan the signature of every online processor directly.
This mode supports multi-signature systems. This scan mode will be slow on
large systems with many processors, and likely requires special permissions
(such as running as the root user). Should the scan fail for any reason, as
a fail-safe measure, it will issue an warning and consider all possible
steppings for every signature it did manage to scan successfully.
\fB\-\-date\-before\fR=\fIYYYY\-MM\-DD\fR and \fB\-\-date\-after\fR=\fIYYYY\-MM\-DD\fR
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