Commit 077ea2bc authored by Florian Weimer's avatar Florian Weimer
Browse files

Editorial changes to the Required Processor Features table

This switches to CPUID bit names where available.  Formatting
is adjusted to match the other tables.

TSC is dropped because its reliability changed since the initial
release of the architecture due to virtualization.

Kernel mode features are removed due to their complex interaction
with virtualization.
parent a70e11ea
Pipeline #173764202 passed with stage
in 3 minutes and 14 seconds
......@@ -5,47 +5,32 @@
\subsection{Processor Architecture}
Any program or kernel can expect that a \xARCH processor implements
the features mentioned in table~\ref{features}. In general a program
has to check itself whether those features are available but for
\xARCH systems, these should always be available.
Table~\ref{features} uses the names for the processor features as
documented in the processor manual.
Any program can expect that an \xARCH processor implements the
features mentioned in table~\ref{features}. Most feature names
correspond to CPUID bits, as described in the processor manual.
Exceptions are OSXFSR are and SCE, which are controlled by bits in the
\reg{cr4} register and the \verb|IA32_EFER| MSR.
\caption{Required Processor Features}\label{features}
Feature & Comment\\
\multicolumn{2}{c}{Features need for programs}\\
fpu & Necessary for \code{long double}, MMX\\
tsc & User-visible\\
cx8 & User-visible\\
cmov& User-visible\\
mmx & User-visible\\
sse & User-visible, required for \code{float}\\
sse2& User-visible, required for \code{double}\\
fxsr& Required for SSE/SSE2 \\
syscall& For calling the kernel\\
\multicolumn{2}{c}{Features need in the kernel}\\
pae& This kind of page tables is used \\
pse& PAE needs PSE.\\
msr & At least needed to enter long mode\\
pge & Kernel optimization\\
pat & Kernel optimization\\
clflush& Kernel optimization\\
& \multicolumn{1}{l}{\rmfamily Example instruction} \\\hline
CMOV & cmov \\
CX8 & cmpxchg8b \\
FPU & fld \\
FXSR & fxsave \\
MMX & emms \\
OSFXSR & fxsave \\
SCE & syscall \\
SSE & cvtss2si \\
SSE2 & cvtpi2pd \\
\subsection{Data Representation}
Within this specification, the term \emph{\textindex{\byte{}}} refers to
......@@ -37,6 +37,9 @@
% >{} constructs for the tabular environment.
% Version number of document - increment occasionally ;-)
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