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authorPaolo Bonzini <pbonzini@redhat.com>2016-10-06 16:49:03 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2016-10-07 10:05:33 +0200
commit77d47e16929b063570a78a264746dc0e8adb85e7 (patch)
treeca5b8e91aa8f4cc9f049ff93fd126bd081a0b2b1 /qemu-tech.texi
parent72bd94c578a4459924e415115b43c21b8ad6cdbd (diff)
downloadqemu-arm-77d47e16929b063570a78a264746dc0e8adb85e7.tar.gz
qemu-tech: reorganize content
Split more parts into separate chapters, place comparison last, rename "Introduction" to "CPU emulation". Reviewed-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'qemu-tech.texi')
-rw-r--r--qemu-tech.texi171
1 files changed, 74 insertions, 97 deletions
diff --git a/qemu-tech.texi b/qemu-tech.texi
index adfb53b7f9..2e499a7c5a 100644
--- a/qemu-tech.texi
+++ b/qemu-tech.texi
@@ -29,27 +29,29 @@
@top
@menu
-* Introduction::
-* QEMU Internals::
+* CPU emulation::
+* Translator Internals::
+* Device emulation::
+* QEMU compared to other emulators::
+* Bibliography::
@end menu
@end ifnottex
@contents
-@node Introduction
-@chapter Introduction
+@node CPU emulation
+@chapter CPU emulation
@menu
-* intro_x86_emulation:: x86 and x86-64 emulation
-* intro_arm_emulation:: ARM emulation
-* intro_mips_emulation:: MIPS emulation
-* intro_ppc_emulation:: PowerPC emulation
-* intro_sparc_emulation:: Sparc32 and Sparc64 emulation
-* intro_xtensa_emulation:: Xtensa emulation
-* intro_other_emulation:: Other CPU emulation
+* x86:: x86 and x86-64 emulation
+* ARM:: ARM emulation
+* MIPS:: MIPS emulation
+* PPC:: PowerPC emulation
+* SPARC:: Sparc32 and Sparc64 emulation
+* Xtensa:: Xtensa emulation
@end menu
-@node intro_x86_emulation
+@node x86
@section x86 and x86-64 emulation
QEMU x86 target features:
@@ -84,7 +86,7 @@ normal use.
@end itemize
-@node intro_arm_emulation
+@node ARM
@section ARM emulation
@itemize
@@ -97,7 +99,7 @@ normal use.
@end itemize
-@node intro_mips_emulation
+@node MIPS
@section MIPS emulation
@itemize
@@ -124,7 +126,7 @@ Current QEMU limitations:
@end itemize
-@node intro_ppc_emulation
+@node PPC
@section PowerPC emulation
@itemize
@@ -136,7 +138,7 @@ FPU and MMU.
@end itemize
-@node intro_sparc_emulation
+@node SPARC
@section Sparc32 and Sparc64 emulation
@itemize
@@ -164,7 +166,7 @@ Current QEMU limitations:
@end itemize
-@node intro_xtensa_emulation
+@node Xtensa
@section Xtensa emulation
@itemize
@@ -189,94 +191,18 @@ may be created from overlay with minimal amount of hand-written code.
@end itemize
-@node intro_other_emulation
-@section Other CPU emulation
-
-In addition to the above, QEMU supports emulation of other CPUs with
-varying levels of success. These are:
-
-@itemize
-
-@item
-Alpha
-@item
-CRIS
-@item
-M68k
-@item
-SH4
-@end itemize
-
-@node QEMU Internals
-@chapter QEMU Internals
+@node Translator Internals
+@chapter Translator Internals
@menu
-* QEMU compared to other emulators::
-* Portable dynamic translation::
* CPU state optimisations::
* Translation cache::
* Direct block chaining::
* Self-modifying code and translated code invalidation::
* Exception support::
* MMU emulation::
-* Device emulation::
-* Bibliography::
@end menu
-@node QEMU compared to other emulators
-@section QEMU compared to other emulators
-
-Like bochs [1], QEMU emulates an x86 CPU. But QEMU is much faster than
-bochs as it uses dynamic compilation. Bochs is closely tied to x86 PC
-emulation while QEMU can emulate several processors.
-
-Like Valgrind [2], QEMU does user space emulation and dynamic
-translation. Valgrind is mainly a memory debugger while QEMU has no
-support for it (QEMU could be used to detect out of bound memory
-accesses as Valgrind, but it has no support to track uninitialised data
-as Valgrind does). The Valgrind dynamic translator generates better code
-than QEMU (in particular it does register allocation) but it is closely
-tied to an x86 host and target and has no support for precise exceptions
-and system emulation.
-
-EM86 [3] is the closest project to user space QEMU (and QEMU still uses
-some of its code, in particular the ELF file loader). EM86 was limited
-to an alpha host and used a proprietary and slow interpreter (the
-interpreter part of the FX!32 Digital Win32 code translator [4]).
-
-TWIN from Willows Software was a Windows API emulator like Wine. It is less
-accurate than Wine but includes a protected mode x86 interpreter to launch
-x86 Windows executables. Such an approach has greater potential because most
-of the Windows API is executed natively but it is far more difficult to
-develop because all the data structures and function parameters exchanged
-between the API and the x86 code must be converted.
-
-User mode Linux [5] was the only solution before QEMU to launch a
-Linux kernel as a process while not needing any host kernel
-patches. However, user mode Linux requires heavy kernel patches while
-QEMU accepts unpatched Linux kernels. The price to pay is that QEMU is
-slower.
-
-The Plex86 [6] PC virtualizer is done in the same spirit as the now
-obsolete qemu-fast system emulator. It requires a patched Linux kernel
-to work (you cannot launch the same kernel on your PC), but the
-patches are really small. As it is a PC virtualizer (no emulation is
-done except for some privileged instructions), it has the potential of
-being faster than QEMU. The downside is that a complicated (and
-potentially unsafe) host kernel patch is needed.
-
-The commercial PC Virtualizers (VMWare [7], VirtualPC [8]) are faster
-than QEMU (without virtualization), but they all need specific, proprietary
-and potentially unsafe host drivers. Moreover, they are unable to
-provide cycle exact simulation as an emulator can.
-
-VirtualBox [9], Xen [10] and KVM [11] are based on QEMU. QEMU-SystemC
-[12] uses QEMU to simulate a system where some hardware devices are
-developed in SystemC.
-
-@node Portable dynamic translation
-@section Portable dynamic translation
-
QEMU is a dynamic translator. When it first encounters a piece of code,
it converts it to the host instruction set. Usually dynamic translators
are very complicated and highly CPU dependent. QEMU uses some tricks
@@ -381,7 +307,7 @@ When MMU mappings change, only the chaining of the basic blocks is
reset (i.e. a basic block can no longer jump directly to another one).
@node Device emulation
-@section Device emulation
+@chapter Device emulation
Systems emulated by QEMU are organized by boards. At initialization
phase, each board instantiates a number of CPUs, devices, RAM and
@@ -407,8 +333,59 @@ Usually the devices implement a reset method and register support for
saving and loading of the device state. The devices can also use
timers, especially together with the use of bottom halves (BHs).
+@node QEMU compared to other emulators
+@chapter QEMU compared to other emulators
+
+Like bochs [1], QEMU emulates an x86 CPU. But QEMU is much faster than
+bochs as it uses dynamic compilation. Bochs is closely tied to x86 PC
+emulation while QEMU can emulate several processors.
+
+Like Valgrind [2], QEMU does user space emulation and dynamic
+translation. Valgrind is mainly a memory debugger while QEMU has no
+support for it (QEMU could be used to detect out of bound memory
+accesses as Valgrind, but it has no support to track uninitialised data
+as Valgrind does). The Valgrind dynamic translator generates better code
+than QEMU (in particular it does register allocation) but it is closely
+tied to an x86 host and target and has no support for precise exceptions
+and system emulation.
+
+EM86 [3] is the closest project to user space QEMU (and QEMU still uses
+some of its code, in particular the ELF file loader). EM86 was limited
+to an alpha host and used a proprietary and slow interpreter (the
+interpreter part of the FX!32 Digital Win32 code translator [4]).
+
+TWIN from Willows Software was a Windows API emulator like Wine. It is less
+accurate than Wine but includes a protected mode x86 interpreter to launch
+x86 Windows executables. Such an approach has greater potential because most
+of the Windows API is executed natively but it is far more difficult to
+develop because all the data structures and function parameters exchanged
+between the API and the x86 code must be converted.
+
+User mode Linux [5] was the only solution before QEMU to launch a
+Linux kernel as a process while not needing any host kernel
+patches. However, user mode Linux requires heavy kernel patches while
+QEMU accepts unpatched Linux kernels. The price to pay is that QEMU is
+slower.
+
+The Plex86 [6] PC virtualizer is done in the same spirit as the now
+obsolete qemu-fast system emulator. It requires a patched Linux kernel
+to work (you cannot launch the same kernel on your PC), but the
+patches are really small. As it is a PC virtualizer (no emulation is
+done except for some privileged instructions), it has the potential of
+being faster than QEMU. The downside is that a complicated (and
+potentially unsafe) host kernel patch is needed.
+
+The commercial PC Virtualizers (VMWare [7], VirtualPC [8]) are faster
+than QEMU (without virtualization), but they all need specific, proprietary
+and potentially unsafe host drivers. Moreover, they are unable to
+provide cycle exact simulation as an emulator can.
+
+VirtualBox [9], Xen [10] and KVM [11] are based on QEMU. QEMU-SystemC
+[12] uses QEMU to simulate a system where some hardware devices are
+developed in SystemC.
+
@node Bibliography
-@section Bibliography
+@chapter Bibliography
@table @asis