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authorPeter Maydell <peter.maydell@linaro.org>2019-03-07 15:21:54 +0000
committerPeter Maydell <peter.maydell@linaro.org>2019-03-07 15:21:54 +0000
commit21afe115a49776aa07f4d93d22b9ad133fd183a5 (patch)
tree06c13402442f44873748d983cf1d56b28bcac405 /docs/devel
parent3a75ef6a0fe397b0d36930415be6b123750a6afe (diff)
parentc10e01b996df09f6cb4eceb2b7a9754bece927c9 (diff)
Merge remote-tracking branch 'remotes/pmaydell/tags/pull-sphinx-20190307' into staging
Enable building and installing rST docs with Sphinx # gpg: Signature made Thu 07 Mar 2019 15:05:12 GMT # gpg: using RSA key E1A5C593CD419DE28E8315CF3C2525ED14360CDE # gpg: issuer "peter.maydell@linaro.org" # gpg: Good signature from "Peter Maydell <peter.maydell@linaro.org>" [ultimate] # gpg: aka "Peter Maydell <pmaydell@gmail.com>" [ultimate] # gpg: aka "Peter Maydell <pmaydell@chiark.greenend.org.uk>" [ultimate] # Primary key fingerprint: E1A5 C593 CD41 9DE2 8E83 15CF 3C25 25ED 1436 0CDE * remotes/pmaydell/tags/pull-sphinx-20190307: MAINTAINERS: Add entry for Sphinx documentation infrastructure docs/conf.py: Don't hard-code QEMU version Makefile: Abstract out "identify the pkgversion" code Makefile, configure: Support building rST documentation docs: Provide separate conf.py for each manual we want docs/conf.py: Disable option warnings docs/conf.py: Don't include rST sources in HTML build docs/conf.py: Configure the 'alabaster' theme docs/conf.py: Disable unused _static directory docs: Commit initial files from sphinx-quickstart docs: Convert memory.txt to rst format docs/cpu-hotplug.rst: Fix rST markup issues Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'docs/devel')
-rw-r--r--docs/devel/conf.py15
-rw-r--r--docs/devel/index.rst21
-rw-r--r--docs/devel/memory.rst (renamed from docs/devel/memory.txt)132
3 files changed, 108 insertions, 60 deletions
diff --git a/docs/devel/conf.py b/docs/devel/conf.py
new file mode 100644
index 0000000000..7441f87e7f
--- /dev/null
+++ b/docs/devel/conf.py
@@ -0,0 +1,15 @@
+# -*- coding: utf-8 -*-
+#
+# QEMU documentation build configuration file for the 'devel' manual.
+#
+# This includes the top level conf file and then makes any necessary tweaks.
+import sys
+import os
+
+qemu_docdir = os.path.abspath("..")
+parent_config = os.path.join(qemu_docdir, "conf.py")
+exec(compile(open(parent_config, "rb").read(), parent_config, 'exec'))
+
+# This slightly misuses the 'description', but is the best way to get
+# the manual title to appear in the sidebar.
+html_theme_options['description'] = u'Developer''s Guide'
diff --git a/docs/devel/index.rst b/docs/devel/index.rst
new file mode 100644
index 0000000000..cd0fa6c9ba
--- /dev/null
+++ b/docs/devel/index.rst
@@ -0,0 +1,21 @@
+.. This is the top level page for the 'devel' manual.
+
+
+QEMU Developer's Guide
+======================
+
+This manual documents various parts of the internals of QEMU.
+You only need to read it if you are interested in reading or
+modifying QEMU's source code.
+
+Contents:
+
+.. toctree::
+ :maxdepth: 2
+
+ loads-stores
+ memory
+ migration
+ stable-process
+ testing
+
diff --git a/docs/devel/memory.txt b/docs/devel/memory.rst
index 42577e1d86..b6a4c37ea5 100644
--- a/docs/devel/memory.txt
+++ b/docs/devel/memory.rst
@@ -1,19 +1,20 @@
+==============
The memory API
==============
The memory API models the memory and I/O buses and controllers of a QEMU
machine. It attempts to allow modelling of:
- - ordinary RAM
- - memory-mapped I/O (MMIO)
- - memory controllers that can dynamically reroute physical memory regions
- to different destinations
+- ordinary RAM
+- memory-mapped I/O (MMIO)
+- memory controllers that can dynamically reroute physical memory regions
+ to different destinations
The memory model provides support for
- - tracking RAM changes by the guest
- - setting up coalesced memory for kvm
- - setting up ioeventfd regions for kvm
+- tracking RAM changes by the guest
+- setting up coalesced memory for kvm
+- setting up ioeventfd regions for kvm
Memory is modelled as an acyclic graph of MemoryRegion objects. Sinks
(leaves) are RAM and MMIO regions, while other nodes represent
@@ -98,25 +99,30 @@ ROM device memory region types), this host memory needs to be
copied to the destination on migration. These APIs which allocate
the host memory for you will also register the memory so it is
migrated:
- - memory_region_init_ram()
- - memory_region_init_rom()
- - memory_region_init_rom_device()
+
+- memory_region_init_ram()
+- memory_region_init_rom()
+- memory_region_init_rom_device()
For most devices and boards this is the correct thing. If you
have a special case where you need to manage the migration of
the backing memory yourself, you can call the functions:
- - memory_region_init_ram_nomigrate()
- - memory_region_init_rom_nomigrate()
- - memory_region_init_rom_device_nomigrate()
+
+- memory_region_init_ram_nomigrate()
+- memory_region_init_rom_nomigrate()
+- memory_region_init_rom_device_nomigrate()
+
which only initialize the MemoryRegion and leave handling
migration to the caller.
The functions:
- - memory_region_init_resizeable_ram()
- - memory_region_init_ram_from_file()
- - memory_region_init_ram_from_fd()
- - memory_region_init_ram_ptr()
- - memory_region_init_ram_device_ptr()
+
+- memory_region_init_resizeable_ram()
+- memory_region_init_ram_from_file()
+- memory_region_init_ram_from_fd()
+- memory_region_init_ram_ptr()
+- memory_region_init_ram_device_ptr()
+
are for special cases only, and so they do not automatically
register the backing memory for migration; the caller must
manage migration if necessary.
@@ -218,7 +224,7 @@ For example, suppose we have a container A of size 0x8000 with two subregions
B and C. B is a container mapped at 0x2000, size 0x4000, priority 2; C is
an MMIO region mapped at 0x0, size 0x6000, priority 1. B currently has two
of its own subregions: D of size 0x1000 at offset 0 and E of size 0x1000 at
-offset 0x2000. As a diagram:
+offset 0x2000. As a diagram::
0 1000 2000 3000 4000 5000 6000 7000 8000
|------|------|------|------|------|------|------|------|
@@ -228,8 +234,9 @@ offset 0x2000. As a diagram:
D: [DDDDD]
E: [EEEEE]
-The regions that will be seen within this address range then are:
- [CCCCCCCCCCCC][DDDDD][CCCCC][EEEEE][CCCCC]
+The regions that will be seen within this address range then are::
+
+ [CCCCCCCCCCCC][DDDDD][CCCCC][EEEEE][CCCCC]
Since B has higher priority than C, its subregions appear in the flat map
even where they overlap with C. In ranges where B has not mapped anything
@@ -237,8 +244,9 @@ C's region appears.
If B had provided its own MMIO operations (ie it was not a pure container)
then these would be used for any addresses in its range not handled by
-D or E, and the result would be:
- [CCCCCCCCCCCC][DDDDD][BBBBB][EEEEE][BBBBB]
+D or E, and the result would be::
+
+ [CCCCCCCCCCCC][DDDDD][BBBBB][EEEEE][BBBBB]
Priority values are local to a container, because the priorities of two
regions are only compared when they are both children of the same container.
@@ -257,6 +265,7 @@ guest accesses an address:
- all direct subregions of the root region are matched against the address, in
descending priority order
+
- if the address lies outside the region offset/size, the subregion is
discarded
- if the subregion is a leaf (RAM or MMIO), the search terminates, returning
@@ -270,36 +279,39 @@ guest accesses an address:
address range), then if this is a container with its own MMIO or RAM
backing the search terminates, returning the container itself. Otherwise
we continue with the next subregion in priority order
+
- if none of the subregions match the address then the search terminates
with no match found
Example memory map
------------------
-system_memory: container@0-2^48-1
- |
- +---- lomem: alias@0-0xdfffffff ---> #ram (0-0xdfffffff)
- |
- +---- himem: alias@0x100000000-0x11fffffff ---> #ram (0xe0000000-0xffffffff)
- |
- +---- vga-window: alias@0xa0000-0xbffff ---> #pci (0xa0000-0xbffff)
- | (prio 1)
- |
- +---- pci-hole: alias@0xe0000000-0xffffffff ---> #pci (0xe0000000-0xffffffff)
-
-pci (0-2^32-1)
- |
- +--- vga-area: container@0xa0000-0xbffff
- | |
- | +--- alias@0x00000-0x7fff ---> #vram (0x010000-0x017fff)
- | |
- | +--- alias@0x08000-0xffff ---> #vram (0x020000-0x027fff)
- |
- +---- vram: ram@0xe1000000-0xe1ffffff
- |
- +---- vga-mmio: mmio@0xe2000000-0xe200ffff
-
-ram: ram@0x00000000-0xffffffff
+::
+
+ system_memory: container@0-2^48-1
+ |
+ +---- lomem: alias@0-0xdfffffff ---> #ram (0-0xdfffffff)
+ |
+ +---- himem: alias@0x100000000-0x11fffffff ---> #ram (0xe0000000-0xffffffff)
+ |
+ +---- vga-window: alias@0xa0000-0xbffff ---> #pci (0xa0000-0xbffff)
+ | (prio 1)
+ |
+ +---- pci-hole: alias@0xe0000000-0xffffffff ---> #pci (0xe0000000-0xffffffff)
+
+ pci (0-2^32-1)
+ |
+ +--- vga-area: container@0xa0000-0xbffff
+ | |
+ | +--- alias@0x00000-0x7fff ---> #vram (0x010000-0x017fff)
+ | |
+ | +--- alias@0x08000-0xffff ---> #vram (0x020000-0x027fff)
+ |
+ +---- vram: ram@0xe1000000-0xe1ffffff
+ |
+ +---- vga-mmio: mmio@0xe2000000-0xe200ffff
+
+ ram: ram@0x00000000-0xffffffff
This is a (simplified) PC memory map. The 4GB RAM block is mapped into the
system address space via two aliases: "lomem" is a 1:1 mapping of the first
@@ -336,16 +348,16 @@ rather than completing successfully; those devices can use the
In addition various constraints can be supplied to control how these
callbacks are called:
- - .valid.min_access_size, .valid.max_access_size define the access sizes
- (in bytes) which the device accepts; accesses outside this range will
- have device and bus specific behaviour (ignored, or machine check)
- - .valid.unaligned specifies that the *device being modelled* supports
- unaligned accesses; if false, unaligned accesses will invoke the
- appropriate bus or CPU specific behaviour.
- - .impl.min_access_size, .impl.max_access_size define the access sizes
- (in bytes) supported by the *implementation*; other access sizes will be
- emulated using the ones available. For example a 4-byte write will be
- emulated using four 1-byte writes, if .impl.max_access_size = 1.
- - .impl.unaligned specifies that the *implementation* supports unaligned
- accesses; if false, unaligned accesses will be emulated by two aligned
- accesses.
+- .valid.min_access_size, .valid.max_access_size define the access sizes
+ (in bytes) which the device accepts; accesses outside this range will
+ have device and bus specific behaviour (ignored, or machine check)
+- .valid.unaligned specifies that the *device being modelled* supports
+ unaligned accesses; if false, unaligned accesses will invoke the
+ appropriate bus or CPU specific behaviour.
+- .impl.min_access_size, .impl.max_access_size define the access sizes
+ (in bytes) supported by the *implementation*; other access sizes will be
+ emulated using the ones available. For example a 4-byte write will be
+ emulated using four 1-byte writes, if .impl.max_access_size = 1.
+- .impl.unaligned specifies that the *implementation* supports unaligned
+ accesses; if false, unaligned accesses will be emulated by two aligned
+ accesses.