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Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

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This commit is contained in:
David S. Miller
2012-04-10 14:30:45 -04:00
parent 32ed53b83e f68e556e23
commit 06eb4eafbd
4047 changed files with 104278 additions and 50193 deletions
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Documentation/ABI/stable/sysfs-driver-usb-usbtmc
+1 -1
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@@ -55,7 +55,7 @@ What: /sys/bus/usb/drivers/usbtmc/devices/*/auto_abort
Date: August 2008
Contact: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Description:
This file determines if the the transaction of the USB TMC
This file determines if the transaction of the USB TMC
device is to be automatically aborted if there is any error.
For more details about this, please see the document,
"Universal Serial Bus Test and Measurement Class Specification
Documentation/ABI/testing/debugfs-olpc
+16
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@@ -0,0 +1,16 @@
What: /sys/kernel/debug/olpc-ec/cmd
Date: Dec 2011
KernelVersion: 3.4
Contact: devel@lists.laptop.org
Description:
A generic interface for executing OLPC Embedded Controller commands and
reading their responses.
To execute a command, write data with the format: CC:N A A A A
CC is the (hex) command, N is the count of expected reply bytes, and A A A A
are optional (hex) arguments.
To read the response (if any), read from the generic node after executing
a command. Hex reply bytes will be returned, *whether or not* they came from
the immediately previous command.
Documentation/ABI/testing/sysfs-block-dm
+25
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@@ -0,0 +1,25 @@
What: /sys/block/dm-<num>/dm/name
Date: January 2009
KernelVersion: 2.6.29
Contact: dm-devel@redhat.com
Description: Device-mapper device name.
Read-only string containing mapped device name.
Users: util-linux, device-mapper udev rules
What: /sys/block/dm-<num>/dm/uuid
Date: January 2009
KernelVersion: 2.6.29
Contact: dm-devel@redhat.com
Description: Device-mapper device UUID.
Read-only string containing DM-UUID or empty string
if DM-UUID is not set.
Users: util-linux, device-mapper udev rules
What: /sys/block/dm-<num>/dm/suspended
Date: June 2009
KernelVersion: 2.6.31
Contact: dm-devel@redhat.com
Description: Device-mapper device suspend state.
Contains the value 1 while the device is suspended.
Otherwise it contains 0. Read-only attribute.
Users: util-linux, device-mapper udev rules
Documentation/ABI/testing/sysfs-bus-event_source-devices-format
+14
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@@ -0,0 +1,14 @@
Where: /sys/bus/event_source/devices/<dev>/format
Date: January 2012
Kernel Version: 3.3
Contact: Jiri Olsa <jolsa@redhat.com>
Description:
Attribute group to describe the magic bits that go into
perf_event_attr::config[012] for a particular pmu.
Each attribute of this group defines the 'hardware' bitmask
we want to export, so that userspace can deal with sane
name/value pairs.
Example: 'config1:1,6-10,44'
Defines contents of attribute that occupies bits 1,6-10,44 of
perf_event_attr::config1.
Documentation/ABI/testing/sysfs-driver-samsung-laptop
+18
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@@ -17,3 +17,21 @@ Description: Some Samsung laptops have different "performance levels"
Specifically, not all support the "overclock" option,
and it's still unknown if this value even changes
anything, other than making the user feel a bit better.
What: /sys/devices/platform/samsung/battery_life_extender
Date: December 1, 2011
KernelVersion: 3.3
Contact: Corentin Chary <corentin.chary@gmail.com>
Description: Max battery charge level can be modified, battery cycle
life can be extended by reducing the max battery charge
level.
0 means normal battery mode (100% charge)
1 means battery life extender mode (80% charge)
What: /sys/devices/platform/samsung/usb_charge
Date: December 1, 2011
KernelVersion: 3.3
Contact: Corentin Chary <corentin.chary@gmail.com>
Description: Use your USB ports to charge devices, even
when your laptop is powered off.
1 means enabled, 0 means disabled.
Documentation/ABI/testing/sysfs-firmware-acpi
+20
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@@ -1,3 +1,23 @@
What: /sys/firmware/acpi/bgrt/
Date: January 2012
Contact: Matthew Garrett <mjg@redhat.com>
Description:
The BGRT is an ACPI 5.0 feature that allows the OS
to obtain a copy of the firmware boot splash and
some associated metadata. This is intended to be used
by boot splash applications in order to interact with
the firmware boot splash in order to avoid jarring
transitions.
image: The image bitmap. Currently a 32-bit BMP.
status: 1 if the image is valid, 0 if firmware invalidated it.
type: 0 indicates image is in BMP format.
version: The version of the BGRT. Currently 1.
xoffset: The number of pixels between the left of the screen
and the left edge of the image.
yoffset: The number of pixels between the top of the screen
and the top edge of the image.
What: /sys/firmware/acpi/interrupts/
Date: February 2008
Contact: Len Brown <lenb@kernel.org>
Documentation/CodingStyle
+29
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@@ -793,6 +793,35 @@ own custom mode, or may have some other magic method for making indentation
work correctly.
Chapter 19: Inline assembly
In architecture-specific code, you may need to use inline assembly to interface
with CPU or platform functionality. Don't hesitate to do so when necessary.
However, don't use inline assembly gratuitously when C can do the job. You can
and should poke hardware from C when possible.
Consider writing simple helper functions that wrap common bits of inline
assembly, rather than repeatedly writing them with slight variations. Remember
that inline assembly can use C parameters.
Large, non-trivial assembly functions should go in .S files, with corresponding
C prototypes defined in C header files. The C prototypes for assembly
functions should use "asmlinkage".
You may need to mark your asm statement as volatile, to prevent GCC from
removing it if GCC doesn't notice any side effects. You don't always need to
do so, though, and doing so unnecessarily can limit optimization.
When writing a single inline assembly statement containing multiple
instructions, put each instruction on a separate line in a separate quoted
string, and end each string except the last with \n\t to properly indent the
next instruction in the assembly output:
asm ("magic %reg1, #42\n\t"
"more_magic %reg2, %reg3"
: /* outputs */ : /* inputs */ : /* clobbers */);
Appendix I: References
Documentation/DMA-attributes.txt
+18
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@@ -31,3 +31,21 @@ may be weakly ordered, that is that reads and writes may pass each other.
Since it is optional for platforms to implement DMA_ATTR_WEAK_ORDERING,
those that do not will simply ignore the attribute and exhibit default
behavior.
DMA_ATTR_WRITE_COMBINE
----------------------
DMA_ATTR_WRITE_COMBINE specifies that writes to the mapping may be
buffered to improve performance.
Since it is optional for platforms to implement DMA_ATTR_WRITE_COMBINE,
those that do not will simply ignore the attribute and exhibit default
behavior.
DMA_ATTR_NON_CONSISTENT
-----------------------
DMA_ATTR_NON_CONSISTENT lets the platform to choose to return either
consistent or non-consistent memory as it sees fit. By using this API,
you are guaranteeing to the platform that you have all the correct and
necessary sync points for this memory in the driver.
Documentation/DocBook/device-drivers.tmpl
+17
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@@ -446,4 +446,21 @@ X!Idrivers/video/console/fonts.c
!Edrivers/i2c/i2c-core.c
</chapter>
<chapter id="hsi">
<title>High Speed Synchronous Serial Interface (HSI)</title>
<para>
High Speed Synchronous Serial Interface (HSI) is a
serial interface mainly used for connecting application
engines (APE) with cellular modem engines (CMT) in cellular
handsets.
HSI provides multiplexing for up to 16 logical channels,
low-latency and full duplex communication.
</para>
!Iinclude/linux/hsi/hsi.h
!Edrivers/hsi/hsi.c
</chapter>
</book>
Documentation/Makefile
+1 -1
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@@ -1,3 +1,3 @@
obj-m := DocBook/ accounting/ auxdisplay/ connector/ \
filesystems/ filesystems/configfs/ ia64/ laptops/ networking/ \
pcmcia/ spi/ timers/ vm/ watchdog/src/
pcmcia/ spi/ timers/ watchdog/src/
Documentation/acpi/apei/einj.txt
+8
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@@ -53,6 +53,14 @@ directory apei/einj. The following files are provided.
This file is used to set the second error parameter value. Effect of
parameter depends on error_type specified.
- notrigger
The EINJ mechanism is a two step process. First inject the error, then
perform some actions to trigger it. Setting "notrigger" to 1 skips the
trigger phase, which *may* allow the user to cause the error in some other
context by a simple access to the cpu, memory location, or device that is
the target of the error injection. Whether this actually works depends
on what operations the BIOS actually includes in the trigger phase.
BIOS versions based in the ACPI 4.0 specification have limited options
to control where the errors are injected. Your BIOS may support an
extension (enabled with the param_extension=1 module parameter, or
Documentation/aoe/aoe.txt
+1 -1
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@@ -35,7 +35,7 @@ CREATING DEVICE NODES
sh Documentation/aoe/mkshelf.sh /dev/etherd 0
There is also an autoload script that shows how to edit
/etc/modprobe.conf to ensure that the aoe module is loaded when
/etc/modprobe.d/aoe.conf to ensure that the aoe module is loaded when
necessary.
USING DEVICE NODES
Documentation/aoe/autoload.sh
+2 -2
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@@ -1,8 +1,8 @@
#!/bin/sh
# set aoe to autoload by installing the
# aliases in /etc/modprobe.conf
# aliases in /etc/modprobe.d/
f=/etc/modprobe.conf
f=/etc/modprobe.d/aoe.conf
if test ! -r $f || test ! -w $f; then
echo "cannot configure $f for module autoloading" 1>&2
Documentation/blockdev/floppy.txt
+1 -1
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@@ -49,7 +49,7 @@ you can put:
options floppy omnibook messages
in /etc/modprobe.conf.
in a configuration file in /etc/modprobe.d/.
The floppy driver related options are:
Documentation/cgroups/cpusets.txt
+1 -1
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@@ -217,7 +217,7 @@ and name space for cpusets, with a minimum of additional kernel code.
The cpus and mems files in the root (top_cpuset) cpuset are
read-only. The cpus file automatically tracks the value of
cpu_online_map using a CPU hotplug notifier, and the mems file
cpu_online_mask using a CPU hotplug notifier, and the mems file
automatically tracks the value of node_states[N_HIGH_MEMORY]--i.e.,
nodes with memory--using the cpuset_track_online_nodes() hook.
Documentation/clk.txt
+233
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@@ -0,0 +1,233 @@
The Common Clk Framework
Mike Turquette <mturquette@ti.com>
This document endeavours to explain the common clk framework details,
and how to port a platform over to this framework. It is not yet a
detailed explanation of the clock api in include/linux/clk.h, but
perhaps someday it will include that information.
Part 1 - introduction and interface split
The common clk framework is an interface to control the clock nodes
available on various devices today. This may come in the form of clock
gating, rate adjustment, muxing or other operations. This framework is
enabled with the CONFIG_COMMON_CLK option.
The interface itself is divided into two halves, each shielded from the
details of its counterpart. First is the common definition of struct
clk which unifies the framework-level accounting and infrastructure that
has traditionally been duplicated across a variety of platforms. Second
is a common implementation of the clk.h api, defined in
drivers/clk/clk.c. Finally there is struct clk_ops, whose operations
are invoked by the clk api implementation.
The second half of the interface is comprised of the hardware-specific
callbacks registered with struct clk_ops and the corresponding
hardware-specific structures needed to model a particular clock. For
the remainder of this document any reference to a callback in struct
clk_ops, such as .enable or .set_rate, implies the hardware-specific
implementation of that code. Likewise, references to struct clk_foo
serve as a convenient shorthand for the implementation of the
hardware-specific bits for the hypothetical "foo" hardware.
Tying the two halves of this interface together is struct clk_hw, which
is defined in struct clk_foo and pointed to within struct clk. This
allows easy for navigation between the two discrete halves of the common
clock interface.
Part 2 - common data structures and api
Below is the common struct clk definition from
include/linux/clk-private.h, modified for brevity:
struct clk {
const char *name;
const struct clk_ops *ops;
struct clk_hw *hw;
char **parent_names;
struct clk **parents;
struct clk *parent;
struct hlist_head children;
struct hlist_node child_node;
...
};
The members above make up the core of the clk tree topology. The clk
api itself defines several driver-facing functions which operate on
struct clk. That api is documented in include/linux/clk.h.
Platforms and devices utilizing the common struct clk use the struct
clk_ops pointer in struct clk to perform the hardware-specific parts of
the operations defined in clk.h:
struct clk_ops {
int (*prepare)(struct clk_hw *hw);
void (*unprepare)(struct clk_hw *hw);
int (*enable)(struct clk_hw *hw);
void (*disable)(struct clk_hw *hw);
int (*is_enabled)(struct clk_hw *hw);
unsigned long (*recalc_rate)(struct clk_hw *hw,
unsigned long parent_rate);
long (*round_rate)(struct clk_hw *hw, unsigned long,
unsigned long *);
int (*set_parent)(struct clk_hw *hw, u8 index);
u8 (*get_parent)(struct clk_hw *hw);
int (*set_rate)(struct clk_hw *hw, unsigned long);
void (*init)(struct clk_hw *hw);
};
Part 3 - hardware clk implementations
The strength of the common struct clk comes from its .ops and .hw pointers
which abstract the details of struct clk from the hardware-specific bits, and
vice versa. To illustrate consider the simple gateable clk implementation in
drivers/clk/clk-gate.c:
struct clk_gate {
struct clk_hw hw;
void __iomem *reg;
u8 bit_idx;
...
};
struct clk_gate contains struct clk_hw hw as well as hardware-specific
knowledge about which register and bit controls this clk's gating.
Nothing about clock topology or accounting, such as enable_count or
notifier_count, is needed here. That is all handled by the common
framework code and struct clk.
Let's walk through enabling this clk from driver code:
struct clk *clk;
clk = clk_get(NULL, "my_gateable_clk");
clk_prepare(clk);
clk_enable(clk);
The call graph for clk_enable is very simple:
clk_enable(clk);
clk->ops->enable(clk->hw);
[resolves to...]
clk_gate_enable(hw);
[resolves struct clk gate with to_clk_gate(hw)]
clk_gate_set_bit(gate);
And the definition of clk_gate_set_bit:
static void clk_gate_set_bit(struct clk_gate *gate)
{
u32 reg;
reg = __raw_readl(gate->reg);
reg |= BIT(gate->bit_idx);
writel(reg, gate->reg);
}
Note that to_clk_gate is defined as:
#define to_clk_gate(_hw) container_of(_hw, struct clk_gate, clk)
This pattern of abstraction is used for every clock hardware
representation.
Part 4 - supporting your own clk hardware
When implementing support for a new type of clock it only necessary to
include the following header:
#include <linux/clk-provider.h>
include/linux/clk.h is included within that header and clk-private.h
must never be included from the code which implements the operations for
a clock. More on that below in Part 5.
To construct a clk hardware structure for your platform you must define
the following:
struct clk_foo {
struct clk_hw hw;
... hardware specific data goes here ...
};
To take advantage of your data you'll need to support valid operations
for your clk:
struct clk_ops clk_foo_ops {
.enable = &clk_foo_enable;
.disable = &clk_foo_disable;
};
Implement the above functions using container_of:
#define to_clk_foo(_hw) container_of(_hw, struct clk_foo, hw)
int clk_foo_enable(struct clk_hw *hw)
{
struct clk_foo *foo;
foo = to_clk_foo(hw);
... perform magic on foo ...
return 0;
};
Below is a matrix detailing which clk_ops are mandatory based upon the
hardware capbilities of that clock. A cell marked as "y" means
mandatory, a cell marked as "n" implies that either including that
callback is invalid or otherwise uneccesary. Empty cells are either
optional or must be evaluated on a case-by-case basis.
clock hardware characteristics
-----------------------------------------------------------
| gate | change rate | single parent | multiplexer | root |
|------|-------------|---------------|-------------|------|
.prepare | | | | | |
.unprepare | | | | | |
| | | | | |
.enable | y | | | | |
.disable | y | | | | |
.is_enabled | y | | | | |
| | | | | |
.recalc_rate | | y | | | |
.round_rate | | y | | | |
.set_rate | | y | | | |
| | | | | |
.set_parent | | | n | y | n |
.get_parent | | | n | y | n |
| | | | | |
.init | | | | | |
-----------------------------------------------------------
Finally, register your clock at run-time with a hardware-specific
registration function. This function simply populates struct clk_foo's
data and then passes the common struct clk parameters to the framework
with a call to:
clk_register(...)
See the basic clock types in drivers/clk/clk-*.c for examples.
Part 5 - static initialization of clock data
For platforms with many clocks (often numbering into the hundreds) it
may be desirable to statically initialize some clock data. This
presents a problem since the definition of struct clk should be hidden
from everyone except for the clock core in drivers/clk/clk.c.
To get around this problem struct clk's definition is exposed in
include/linux/clk-private.h along with some macros for more easily
initializing instances of the basic clock types. These clocks must
still be initialized with the common clock framework via a call to
__clk_init.
clk-private.h must NEVER be included by code which implements struct
clk_ops callbacks, nor must it be included by any logic which pokes
around inside of struct clk at run-time. To do so is a layering
violation.
To better enforce this policy, always follow this simple rule: any
statically initialized clock data MUST be defined in a separate file
from the logic that implements its ops. Basically separate the logic
from the data and all is well.
Documentation/cpu-hotplug.txt
+11 -11
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@@ -47,7 +47,7 @@ maxcpus=n Restrict boot time cpus to n. Say if you have 4 cpus, using
other cpus later online, read FAQ's for more info.
additional_cpus=n (*) Use this to limit hotpluggable cpus. This option sets
cpu_possible_map = cpu_present_map + additional_cpus
cpu_possible_mask = cpu_present_mask + additional_cpus
cede_offline={"off","on"} Use this option to disable/enable putting offlined
processors to an extended H_CEDE state on
@@ -64,11 +64,11 @@ should only rely on this to count the # of cpus, but *MUST* not rely
on the apicid values in those tables for disabled apics. In the event
BIOS doesn't mark such hot-pluggable cpus as disabled entries, one could
use this parameter "additional_cpus=x" to represent those cpus in the
cpu_possible_map.
cpu_possible_mask.
possible_cpus=n [s390,x86_64] use this to set hotpluggable cpus.
This option sets possible_cpus bits in
cpu_possible_map. Thus keeping the numbers of bits set
cpu_possible_mask. Thus keeping the numbers of bits set
constant even if the machine gets rebooted.
CPU maps and such
@@ -76,7 +76,7 @@ CPU maps and such
[More on cpumaps and primitive to manipulate, please check
include/linux/cpumask.h that has more descriptive text.]
cpu_possible_map: Bitmap of possible CPUs that can ever be available in the
cpu_possible_mask: Bitmap of possible CPUs that can ever be available in the
system. This is used to allocate some boot time memory for per_cpu variables
that aren't designed to grow/shrink as CPUs are made available or removed.
Once set during boot time discovery phase, the map is static, i.e no bits
@@ -84,13 +84,13 @@ are added or removed anytime. Trimming it accurately for your system needs
upfront can save some boot time memory. See below for how we use heuristics
in x86_64 case to keep this under check.
cpu_online_map: Bitmap of all CPUs currently online. Its set in __cpu_up()
cpu_online_mask: Bitmap of all CPUs currently online. Its set in __cpu_up()
after a cpu is available for kernel scheduling and ready to receive
interrupts from devices. Its cleared when a cpu is brought down using
__cpu_disable(), before which all OS services including interrupts are
migrated to another target CPU.
cpu_present_map: Bitmap of CPUs currently present in the system. Not all
cpu_present_mask: Bitmap of CPUs currently present in the system. Not all
of them may be online. When physical hotplug is processed by the relevant
subsystem (e.g ACPI) can change and new bit either be added or removed
from the map depending on the event is hot-add/hot-remove. There are currently
@@ -99,22 +99,22 @@ at which time hotplug is disabled.
You really dont need to manipulate any of the system cpu maps. They should
be read-only for most use. When setting up per-cpu resources almost always use
cpu_possible_map/for_each_possible_cpu() to iterate.
cpu_possible_mask/for_each_possible_cpu() to iterate.
Never use anything other than cpumask_t to represent bitmap of CPUs.
#include <linux/cpumask.h>
for_each_possible_cpu - Iterate over cpu_possible_map
for_each_online_cpu - Iterate over cpu_online_map
for_each_present_cpu - Iterate over cpu_present_map
for_each_possible_cpu - Iterate over cpu_possible_mask
for_each_online_cpu - Iterate over cpu_online_mask
for_each_present_cpu - Iterate over cpu_present_mask
for_each_cpu_mask(x,mask) - Iterate over some random collection of cpu mask.
#include <linux/cpu.h>
get_online_cpus() and put_online_cpus():
The above calls are used to inhibit cpu hotplug operations. While the
cpu_hotplug.refcount is non zero, the cpu_online_map will not change.
cpu_hotplug.refcount is non zero, the cpu_online_mask will not change.
If you merely need to avoid cpus going away, you could also use
preempt_disable() and preempt_enable() for those sections.
Just remember the critical section cannot call any
Documentation/cpuidle/sysfs.txt
+5
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@@ -36,6 +36,7 @@ drwxr-xr-x 2 root root 0 Feb 8 10:42 state3
/sys/devices/system/cpu/cpu0/cpuidle/state0:
total 0
-r--r--r-- 1 root root 4096 Feb 8 10:42 desc
-rw-r--r-- 1 root root 4096 Feb 8 10:42 disable
-r--r--r-- 1 root root 4096 Feb 8 10:42 latency
-r--r--r-- 1 root root 4096 Feb 8 10:42 name
-r--r--r-- 1 root root 4096 Feb 8 10:42 power
@@ -45,6 +46,7 @@ total 0
/sys/devices/system/cpu/cpu0/cpuidle/state1:
total 0
-r--r--r-- 1 root root 4096 Feb 8 10:42 desc
-rw-r--r-- 1 root root 4096 Feb 8 10:42 disable
-r--r--r-- 1 root root 4096 Feb 8 10:42 latency
-r--r--r-- 1 root root 4096 Feb 8 10:42 name
-r--r--r-- 1 root root 4096 Feb 8 10:42 power
@@ -54,6 +56,7 @@ total 0
/sys/devices/system/cpu/cpu0/cpuidle/state2:
total 0
-r--r--r-- 1 root root 4096 Feb 8 10:42 desc
-rw-r--r-- 1 root root 4096 Feb 8 10:42 disable
-r--r--r-- 1 root root 4096 Feb 8 10:42 latency
-r--r--r-- 1 root root 4096 Feb 8 10:42 name
-r--r--r-- 1 root root 4096 Feb 8 10:42 power
@@ -63,6 +66,7 @@ total 0
/sys/devices/system/cpu/cpu0/cpuidle/state3:
total 0
-r--r--r-- 1 root root 4096 Feb 8 10:42 desc
-rw-r--r-- 1 root root 4096 Feb 8 10:42 disable
-r--r--r-- 1 root root 4096 Feb 8 10:42 latency
-r--r--r-- 1 root root 4096 Feb 8 10:42 name
-r--r--r-- 1 root root 4096 Feb 8 10:42 power
@@ -72,6 +76,7 @@ total 0
* desc : Small description about the idle state (string)
* disable : Option to disable this idle state (bool)
* latency : Latency to exit out of this idle state (in microseconds)
* name : Name of the idle state (string)
* power : Power consumed while in this idle state (in milliwatts)
Documentation/device-mapper/thin-provisioning.txt
+50 -15
View File
@@ -75,10 +75,12 @@ less sharing than average you'll need a larger-than-average metadata device.
As a guide, we suggest you calculate the number of bytes to use in the
metadata device as 48 * $data_dev_size / $data_block_size but round it up
to 2MB if the answer is smaller. The largest size supported is 16GB.
to 2MB if the answer is smaller. If you're creating large numbers of
snapshots which are recording large amounts of change, you may find you
need to increase this.
If you're creating large numbers of snapshots which are recording large
amounts of change, you may need find you need to increase this.
The largest size supported is 16GB: If the device is larger,
a warning will be issued and the excess space will not be used.
Reloading a pool table
----------------------
@@ -167,6 +169,38 @@ ii) Using an internal snapshot.
dmsetup create snap --table "0 2097152 thin /dev/mapper/pool 1"
External snapshots
------------------
You can use an external _read only_ device as an origin for a
thinly-provisioned volume. Any read to an unprovisioned area of the
thin device will be passed through to the origin. Writes trigger
the allocation of new blocks as usual.
One use case for this is VM hosts that want to run guests on
thinly-provisioned volumes but have the base image on another device
(possibly shared between many VMs).
You must not write to the origin device if you use this technique!
Of course, you may write to the thin device and take internal snapshots
of the thin volume.
i) Creating a snapshot of an external device
This is the same as creating a thin device.
You don't mention the origin at this stage.
dmsetup message /dev/mapper/pool 0 "create_thin 0"
ii) Using a snapshot of an external device.
Append an extra parameter to the thin target specifying the origin:
dmsetup create snap --table "0 2097152 thin /dev/mapper/pool 0 /dev/image"
N.B. All descendants (internal snapshots) of this snapshot require the
same extra origin parameter.
Deactivation
------------
@@ -189,7 +223,13 @@ i) Constructor
<low water mark (blocks)> [<number of feature args> [<arg>]*]
Optional feature arguments:
- 'skip_block_zeroing': skips the zeroing of newly-provisioned blocks.
skip_block_zeroing: Skip the zeroing of newly-provisioned blocks.
ignore_discard: Disable discard support.
no_discard_passdown: Don't pass discards down to the underlying
data device, but just remove the mapping.
Data block size must be between 64KB (128 sectors) and 1GB
(2097152 sectors) inclusive.
@@ -237,16 +277,6 @@ iii) Messages
Deletes a thin device. Irreversible.
trim <dev id> <new size in sectors>
Delete mappings from the end of a thin device. Irreversible.
You might want to use this if you're reducing the size of
your thinly-provisioned device. In many cases, due to the
sharing of blocks between devices, it is not possible to
determine in advance how much space 'trim' will release. (In
future a userspace tool might be able to perform this
calculation.)
set_transaction_id <current id> <new id>
Userland volume managers, such as LVM, need a way to
@@ -262,7 +292,7 @@ iii) Messages
i) Constructor
thin <pool dev> <dev id>
thin <pool dev> <dev id> [<external origin dev>]
pool dev:
the thin-pool device, e.g. /dev/mapper/my_pool or 253:0
@@ -271,6 +301,11 @@ i) Constructor
the internal device identifier of the device to be
activated.
external origin dev:
an optional block device outside the pool to be treated as a
read-only snapshot origin: reads to unprovisioned areas of the
thin target will be mapped to this device.
The pool doesn't store any size against the thin devices. If you
load a thin target that is smaller than you've been using previously,
then you'll have no access to blocks mapped beyond the end. If you
Documentation/device-mapper/verity.txt
+194
View File
@@ -0,0 +1,194 @@
dm-verity
==========
Device-Mapper's "verity" target provides transparent integrity checking of
block devices using a cryptographic digest provided by the kernel crypto API.
This target is read-only.
Construction Parameters
=======================
<version> <dev> <hash_dev> <hash_start>
<data_block_size> <hash_block_size>
<num_data_blocks> <hash_start_block>
<algorithm> <digest> <salt>
<version>
This is the version number of the on-disk format.
0 is the original format used in the Chromium OS.
The salt is appended when hashing, digests are stored continuously and
the rest of the block is padded with zeros.
1 is the current format that should be used for new devices.
The salt is prepended when hashing and each digest is
padded with zeros to the power of two.
<dev>
This is the device containing the data the integrity of which needs to be
checked. It may be specified as a path, like /dev/sdaX, or a device number,
<major>:<minor>.
<hash_dev>
This is the device that that supplies the hash tree data. It may be
specified similarly to the device path and may be the same device. If the
same device is used, the hash_start should be outside of the dm-verity
configured device size.
<data_block_size>
The block size on a data device. Each block corresponds to one digest on
the hash device.
<hash_block_size>
The size of a hash block.
<num_data_blocks>
The number of data blocks on the data device. Additional blocks are
inaccessible. You can place hashes to the same partition as data, in this
case hashes are placed after <num_data_blocks>.
<hash_start_block>
This is the offset, in <hash_block_size>-blocks, from the start of hash_dev
to the root block of the hash tree.
<algorithm>
The cryptographic hash algorithm used for this device. This should
be the name of the algorithm, like "sha1".
<digest>
The hexadecimal encoding of the cryptographic hash of the root hash block
and the salt. This hash should be trusted as there is no other authenticity
beyond this point.
<salt>
The hexadecimal encoding of the salt value.
Theory of operation
===================
dm-verity is meant to be setup as part of a verified boot path. This
may be anything ranging from a boot using tboot or trustedgrub to just
booting from a known-good device (like a USB drive or CD).
When a dm-verity device is configured, it is expected that the caller
has been authenticated in some way (cryptographic signatures, etc).
After instantiation, all hashes will be verified on-demand during
disk access. If they cannot be verified up to the root node of the
tree, the root hash, then the I/O will fail. This should identify
tampering with any data on the device and the hash data.
Cryptographic hashes are used to assert the integrity of the device on a
per-block basis. This allows for a lightweight hash computation on first read
into the page cache. Block hashes are stored linearly-aligned to the nearest
block the size of a page.
Hash Tree
---------
Each node in the tree is a cryptographic hash. If it is a leaf node, the hash
is of some block data on disk. If it is an intermediary node, then the hash is
of a number of child nodes.
Each entry in the tree is a collection of neighboring nodes that fit in one
block. The number is determined based on block_size and the size of the
selected cryptographic digest algorithm. The hashes are linearly-ordered in
this entry and any unaligned trailing space is ignored but included when
calculating the parent node.
The tree looks something like:
alg = sha256, num_blocks = 32768, block_size = 4096
[ root ]
/ . . . \
[entry_0] [entry_1]
/ . . . \ . . . \
[entry_0_0] . . . [entry_0_127] . . . . [entry_1_127]
/ ... \ / . . . \ / \
blk_0 ... blk_127 blk_16256 blk_16383 blk_32640 . . . blk_32767
On-disk format
==============
Below is the recommended on-disk format. The verity kernel code does not
read the on-disk header. It only reads the hash blocks which directly
follow the header. It is expected that a user-space tool will verify the
integrity of the verity_header and then call dmsetup with the correct
parameters. Alternatively, the header can be omitted and the dmsetup
parameters can be passed via the kernel command-line in a rooted chain
of trust where the command-line is verified.
The on-disk format is especially useful in cases where the hash blocks
are on a separate partition. The magic number allows easy identification
of the partition contents. Alternatively, the hash blocks can be stored
in the same partition as the data to be verified. In such a configuration
the filesystem on the partition would be sized a little smaller than
the full-partition, leaving room for the hash blocks.
struct superblock {
uint8_t signature[8]
"verity\0\0";
uint8_t version;
1 - current format
uint8_t data_block_bits;
log2(data block size)
uint8_t hash_block_bits;
log2(hash block size)
uint8_t pad1[1];
zero padding
uint16_t salt_size;
big-endian salt size
uint8_t pad2[2];
zero padding
uint32_t data_blocks_hi;
big-endian high 32 bits of the 64-bit number of data blocks
uint32_t data_blocks_lo;
big-endian low 32 bits of the 64-bit number of data blocks
uint8_t algorithm[16];
cryptographic algorithm
uint8_t salt[384];
salt (the salt size is specified above)
uint8_t pad3[88];
zero padding to 512-byte boundary
}
Directly following the header (and with sector number padded to the next hash
block boundary) are the hash blocks which are stored a depth at a time
(starting from the root), sorted in order of increasing index.
Status
======
V (for Valid) is returned if every check performed so far was valid.
If any check failed, C (for Corruption) is returned.
Example
=======
Setup a device:
dmsetup create vroot --table \
"0 2097152 "\
"verity 1 /dev/sda1 /dev/sda2 4096 4096 2097152 1 "\
"4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076 "\
"1234000000000000000000000000000000000000000000000000000000000000"
A command line tool veritysetup is available to compute or verify
the hash tree or activate the kernel driver. This is available from
the LVM2 upstream repository and may be supplied as a package called
device-mapper-verity-tools:
git://sources.redhat.com/git/lvm2
http://sourceware.org/git/?p=lvm2.git
http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/verity?cvsroot=lvm2
veritysetup -a vroot /dev/sda1 /dev/sda2 \
4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076

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