summaryrefslogtreecommitdiffstats
path: root/Documentation/virtual
diff options
context:
space:
mode:
authorLuis R. Rodriguez <mcgrof@suse.com>2015-02-13 17:13:40 +1030
committerRusty Russell <rusty@rustcorp.com.au>2015-02-13 17:15:44 +1030
commita2e199915725e666772dd077dbffbef154e58096 (patch)
tree10b984c9ca4f9c1957808d39603ee095f0c7d71a /Documentation/virtual
parentd9bab50aa46ce46dd4537d455eb13b200cdac516 (diff)
downloadlinux-a2e199915725e666772dd077dbffbef154e58096.tar.bz2
virtual: Documentation: simplify and generalize paravirt_ops.txt
The general documentation we have for pv_ops is currenty present on the IA64 docs, but since this documentation covers IA64 xen enablement and IA64 Xen support got ripped out a while ago through commit d52eefb47 present since v3.14-rc1 lets just simplify, generalize and move the pv_ops documentation to a shared place. Cc: Isaku Yamahata <yamahata@valinux.co.jp> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Alok Kataria <akataria@vmware.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: virtualization@lists.linux-foundation.org Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: xen-devel@lists.xenproject.org Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'Documentation/virtual')
-rw-r--r--Documentation/virtual/00-INDEX3
-rw-r--r--Documentation/virtual/paravirt_ops.txt32
2 files changed, 35 insertions, 0 deletions
diff --git a/Documentation/virtual/00-INDEX b/Documentation/virtual/00-INDEX
index e952d30bbf0f..af0d23968ee7 100644
--- a/Documentation/virtual/00-INDEX
+++ b/Documentation/virtual/00-INDEX
@@ -2,6 +2,9 @@ Virtualization support in the Linux kernel.
00-INDEX
- this file.
+
+paravirt_ops.txt
+ - Describes the Linux kernel pv_ops to support different hypervisors
kvm/
- Kernel Virtual Machine. See also http://linux-kvm.org
uml/
diff --git a/Documentation/virtual/paravirt_ops.txt b/Documentation/virtual/paravirt_ops.txt
new file mode 100644
index 000000000000..d4881c00e339
--- /dev/null
+++ b/Documentation/virtual/paravirt_ops.txt
@@ -0,0 +1,32 @@
+Paravirt_ops
+============
+
+Linux provides support for different hypervisor virtualization technologies.
+Historically different binary kernels would be required in order to support
+different hypervisors, this restriction was removed with pv_ops.
+Linux pv_ops is a virtualization API which enables support for different
+hypervisors. It allows each hypervisor to override critical operations and
+allows a single kernel binary to run on all supported execution environments
+including native machine -- without any hypervisors.
+
+pv_ops provides a set of function pointers which represent operations
+corresponding to low level critical instructions and high level
+functionalities in various areas. pv-ops allows for optimizations at run
+time by enabling binary patching of the low-ops critical operations
+at boot time.
+
+pv_ops operations are classified into three categories:
+
+- simple indirect call
+ These operations correspond to high level functionality where it is
+ known that the overhead of indirect call isn't very important.
+
+- indirect call which allows optimization with binary patch
+ Usually these operations correspond to low level critical instructions. They
+ are called frequently and are performance critical. The overhead is
+ very important.
+
+- a set of macros for hand written assembly code
+ Hand written assembly codes (.S files) also need paravirtualization
+ because they include sensitive instructions or some of code paths in
+ them are very performance critical.