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r: 10853
b: refs/heads/master
c: 0ace57a
h: refs/heads/master
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  10851: 3bf96f7
v: v3
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Tony Luck committed Oct 28, 2005
1 parent d01848c commit c4ea917
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2 changes: 1 addition & 1 deletion [refs]
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@@ -1,2 +1,2 @@
---
refs/heads/master: 44c451208da397438e7062393aeb3a19ddb76a60
refs/heads/master: 0ace57a96bf299f6d46fd49e3edbaf79f500d160
30 changes: 30 additions & 0 deletions trunk/.gitignore
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#
# NOTE! Don't add files that are generated in specific
# subdirectories here. Add them in the ".gitignore" file
# in that subdirectory instead.
#
# Normal rules
#
.*
*.o
*.a
*.s
*.ko
*.mod.c

#
# Top-level generic files
#
vmlinux*
System.map
Module.symvers

#
# Generated include files
#
include/asm
include/config
include/linux/autoconf.h
include/linux/compile.h
include/linux/version.h

10 changes: 10 additions & 0 deletions trunk/Documentation/Changes
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Expand Up @@ -237,6 +237,12 @@ udev
udev is a userspace application for populating /dev dynamically with
only entries for devices actually present. udev replaces devfs.

FUSE
----

Needs libfuse 2.4.0 or later. Absolute minimum is 2.3.0 but mount
options 'direct_io' and 'kernel_cache' won't work.

Networking
==========

Expand Down Expand Up @@ -390,6 +396,10 @@ udev
----
o <http://www.kernel.org/pub/linux/utils/kernel/hotplug/udev.html>

FUSE
----
o <http://sourceforge.net/projects/fuse>

Networking
**********

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2 changes: 1 addition & 1 deletion trunk/Documentation/DocBook/kernel-hacking.tmpl
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Expand Up @@ -1105,7 +1105,7 @@ static struct block_device_operations opt_fops = {
</listitem>
<listitem>
<para>
Function names as strings (__func__).
Function names as strings (__FUNCTION__).
</para>
</listitem>
<listitem>
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86 changes: 85 additions & 1 deletion trunk/Documentation/SubmittingPatches
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Expand Up @@ -301,15 +301,99 @@ now, but you can do this to mark internal company procedures or just
point out some special detail about the sign-off.


12) The canonical patch format

12) More references for submitting patches
The canonical patch subject line is:

Subject: [PATCH 001/123] subsystem: summary phrase

The canonical patch message body contains the following:

- A "from" line specifying the patch author.

- An empty line.

- The body of the explanation, which will be copied to the
permanent changelog to describe this patch.

- The "Signed-off-by:" lines, described above, which will
also go in the changelog.

- A marker line containing simply "---".

- Any additional comments not suitable for the changelog.

- The actual patch (diff output).

The Subject line format makes it very easy to sort the emails
alphabetically by subject line - pretty much any email reader will
support that - since because the sequence number is zero-padded,
the numerical and alphabetic sort is the same.

The "subsystem" in the email's Subject should identify which
area or subsystem of the kernel is being patched.

The "summary phrase" in the email's Subject should concisely
describe the patch which that email contains. The "summary
phrase" should not be a filename. Do not use the same "summary
phrase" for every patch in a whole patch series.

Bear in mind that the "summary phrase" of your email becomes
a globally-unique identifier for that patch. It propagates
all the way into the git changelog. The "summary phrase" may
later be used in developer discussions which refer to the patch.
People will want to google for the "summary phrase" to read
discussion regarding that patch.

A couple of example Subjects:

Subject: [patch 2/5] ext2: improve scalability of bitmap searching
Subject: [PATCHv2 001/207] x86: fix eflags tracking

The "from" line must be the very first line in the message body,
and has the form:

From: Original Author <author@example.com>

The "from" line specifies who will be credited as the author of the
patch in the permanent changelog. If the "from" line is missing,
then the "From:" line from the email header will be used to determine
the patch author in the changelog.

The explanation body will be committed to the permanent source
changelog, so should make sense to a competent reader who has long
since forgotten the immediate details of the discussion that might
have led to this patch.

The "---" marker line serves the essential purpose of marking for patch
handling tools where the changelog message ends.

One good use for the additional comments after the "---" marker is for
a diffstat, to show what files have changed, and the number of inserted
and deleted lines per file. A diffstat is especially useful on bigger
patches. Other comments relevant only to the moment or the maintainer,
not suitable for the permanent changelog, should also go here.

See more details on the proper patch format in the following
references.


13) More references for submitting patches

Andrew Morton, "The perfect patch" (tpp).
<http://www.zip.com.au/~akpm/linux/patches/stuff/tpp.txt>

Jeff Garzik, "Linux kernel patch submission format."
<http://linux.yyz.us/patch-format.html>

Greg KH, "How to piss off a kernel subsystem maintainer"
<http://www.kroah.com/log/2005/03/31/>

Kernel Documentation/CodingStyle
<http://sosdg.org/~coywolf/lxr/source/Documentation/CodingStyle>

Linus Torvald's mail on the canonical patch format:
<http://lkml.org/lkml/2005/4/7/183>


-----------------------------------
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44 changes: 44 additions & 0 deletions trunk/Documentation/connector/connector.txt
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Expand Up @@ -131,3 +131,47 @@ Netlink itself is not reliable protocol, that means that messages can
be lost due to memory pressure or process' receiving queue overflowed,
so caller is warned must be prepared. That is why struct cn_msg [main
connector's message header] contains u32 seq and u32 ack fields.

/*****************************************/
Userspace usage.
/*****************************************/
2.6.14 has a new netlink socket implementation, which by default does not
allow to send data to netlink groups other than 1.
So, if to use netlink socket (for example using connector)
with different group number userspace application must subscribe to
that group. It can be achieved by following pseudocode:

s = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);

l_local.nl_family = AF_NETLINK;
l_local.nl_groups = 12345;
l_local.nl_pid = 0;

if (bind(s, (struct sockaddr *)&l_local, sizeof(struct sockaddr_nl)) == -1) {
perror("bind");
close(s);
return -1;
}

{
int on = l_local.nl_groups;
setsockopt(s, 270, 1, &on, sizeof(on));
}

Where 270 above is SOL_NETLINK, and 1 is a NETLINK_ADD_MEMBERSHIP socket
option. To drop multicast subscription one should call above socket option
with NETLINK_DROP_MEMBERSHIP parameter which is defined as 0.

2.6.14 netlink code only allows to select a group which is less or equal to
the maximum group number, which is used at netlink_kernel_create() time.
In case of connector it is CN_NETLINK_USERS + 0xf, so if you want to use
group number 12345, you must increment CN_NETLINK_USERS to that number.
Additional 0xf numbers are allocated to be used by non-in-kernel users.

Due to this limitation, group 0xffffffff does not work now, so one can
not use add/remove connector's group notifications, but as far as I know,
only cn_test.c test module used it.

Some work in netlink area is still being done, so things can be changed in
2.6.15 timeframe, if it will happen, documentation will be updated for that
kernel.
38 changes: 28 additions & 10 deletions trunk/Documentation/dell_rbu.txt
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Expand Up @@ -35,6 +35,7 @@ The driver load creates the following directories under the /sys file system.
/sys/class/firmware/dell_rbu/data
/sys/devices/platform/dell_rbu/image_type
/sys/devices/platform/dell_rbu/data
/sys/devices/platform/dell_rbu/packet_size

The driver supports two types of update mechanism; monolithic and packetized.
These update mechanism depends upon the BIOS currently running on the system.
Expand All @@ -47,8 +48,26 @@ By default the driver uses monolithic memory for the update type. This can be
changed to packets during the driver load time by specifying the load
parameter image_type=packet. This can also be changed later as below
echo packet > /sys/devices/platform/dell_rbu/image_type
Also echoing either mono ,packet or init in to image_type will free up the
memory allocated by the driver.

In packet update mode the packet size has to be given before any packets can
be downloaded. It is done as below
echo XXXX > /sys/devices/platform/dell_rbu/packet_size
In the packet update mechanism, the user neesd to create a new file having
packets of data arranged back to back. It can be done as follows
The user creates packets header, gets the chunk of the BIOS image and
placs it next to the packetheader; now, the packetheader + BIOS image chunk
added to geather should match the specified packet_size. This makes one
packet, the user needs to create more such packets out of the entire BIOS
image file and then arrange all these packets back to back in to one single
file.
This file is then copied to /sys/class/firmware/dell_rbu/data.
Once this file gets to the driver, the driver extracts packet_size data from
the file and spreads it accross the physical memory in contiguous packet_sized
space.
This method makes sure that all the packets get to the driver in a single operation.

In monolithic update the user simply get the BIOS image (.hdr file) and copies
to the data file as is without any change to the BIOS image itself.

Do the steps below to download the BIOS image.
1) echo 1 > /sys/class/firmware/dell_rbu/loading
Expand All @@ -58,23 +77,22 @@ Do the steps below to download the BIOS image.
The /sys/class/firmware/dell_rbu/ entries will remain till the following is
done.
echo -1 > /sys/class/firmware/dell_rbu/loading.
Until this step is completed the drivr cannot be unloaded.
Until this step is completed the driver cannot be unloaded.
Also echoing either mono ,packet or init in to image_type will free up the
memory allocated by the driver.

If an user by accident executes steps 1 and 3 above without executing step 2;
it will make the /sys/class/firmware/dell_rbu/ entries to disappear.
The entries can be recreated by doing the following
echo init > /sys/devices/platform/dell_rbu/image_type
NOTE: echoing init in image_type does not change it original value.

Also the driver provides /sys/devices/platform/dell_rbu/data readonly file to
read back the image downloaded. This is useful in case of packet update
mechanism where the above steps 1,2,3 will repeated for every packet.
By reading the /sys/devices/platform/dell_rbu/data file all packet data
downloaded can be verified in a single file.
The packets are arranged in this file one after the other in a FIFO order.
read back the image downloaded.

NOTE:
This driver requires a patch for firmware_class.c which has the addition
of request_firmware_nowait_nohotplug function to wortk
This driver requires a patch for firmware_class.c which has the modified
request_firmware_nowait function.
Also after updating the BIOS image an user mdoe application neeeds to execute
code which message the BIOS update request to the BIOS. So on the next reboot
the BIOS knows about the new image downloaded and it updates it self.
Expand Down
73 changes: 73 additions & 0 deletions trunk/Documentation/device-mapper/snapshot.txt
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Device-mapper snapshot support
==============================

Device-mapper allows you, without massive data copying:

*) To create snapshots of any block device i.e. mountable, saved states of
the block device which are also writable without interfering with the
original content;
*) To create device "forks", i.e. multiple different versions of the
same data stream.


In both cases, dm copies only the chunks of data that get changed and
uses a separate copy-on-write (COW) block device for storage.


There are two dm targets available: snapshot and snapshot-origin.

*) snapshot-origin <origin>

which will normally have one or more snapshots based on it.
You must create the snapshot-origin device before you can create snapshots.
Reads will be mapped directly to the backing device. For each write, the
original data will be saved in the <COW device> of each snapshot to keep
its visible content unchanged, at least until the <COW device> fills up.


*) snapshot <origin> <COW device> <persistent?> <chunksize>

A snapshot is created of the <origin> block device. Changed chunks of
<chunksize> sectors will be stored on the <COW device>. Writes will
only go to the <COW device>. Reads will come from the <COW device> or
from <origin> for unchanged data. <COW device> will often be
smaller than the origin and if it fills up the snapshot will become
useless and be disabled, returning errors. So it is important to monitor
the amount of free space and expand the <COW device> before it fills up.

<persistent?> is P (Persistent) or N (Not persistent - will not survive
after reboot).


How this is used by LVM2
========================
When you create the first LVM2 snapshot of a volume, four dm devices are used:

1) a device containing the original mapping table of the source volume;
2) a device used as the <COW device>;
3) a "snapshot" device, combining #1 and #2, which is the visible snapshot
volume;
4) the "original" volume (which uses the device number used by the original
source volume), whose table is replaced by a "snapshot-origin" mapping
from device #1.

A fixed naming scheme is used, so with the following commands:

lvcreate -L 1G -n base volumeGroup
lvcreate -L 100M --snapshot -n snap volumeGroup/base

we'll have this situation (with volumes in above order):

# dmsetup table|grep volumeGroup

volumeGroup-base-real: 0 2097152 linear 8:19 384
volumeGroup-snap-cow: 0 204800 linear 8:19 2097536
volumeGroup-snap: 0 2097152 snapshot 254:11 254:12 P 16
volumeGroup-base: 0 2097152 snapshot-origin 254:11

# ls -lL /dev/mapper/volumeGroup-*
brw------- 1 root root 254, 11 29 ago 18:15 /dev/mapper/volumeGroup-base-real
brw------- 1 root root 254, 12 29 ago 18:15 /dev/mapper/volumeGroup-snap-cow
brw------- 1 root root 254, 13 29 ago 18:15 /dev/mapper/volumeGroup-snap
brw------- 1 root root 254, 10 29 ago 18:14 /dev/mapper/volumeGroup-base

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