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r: 74397
b: refs/heads/master
c: e1cca7e
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  74395: 1a2adba
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Linus Torvalds committed Nov 30, 2007
1 parent 8e10bc3 commit 14f1a77
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2 changes: 1 addition & 1 deletion [refs]
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---
refs/heads/master: 16252da654800461e0e1c32697cb59f4cda15aa9
refs/heads/master: e1cca7e8d484390169777b423a7fe46c7021fec1
2 changes: 2 additions & 0 deletions trunk/Documentation/00-INDEX
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Expand Up @@ -262,6 +262,8 @@ mtrr.txt
- how to use PPro Memory Type Range Registers to increase performance.
mutex-design.txt
- info on the generic mutex subsystem.
namespaces/
- directory with various information about namespaces
nbd.txt
- info on a TCP implementation of a network block device.
netlabel/
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2 changes: 1 addition & 1 deletion trunk/Documentation/DocBook/Makefile
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Expand Up @@ -11,7 +11,7 @@ DOCBOOKS := wanbook.xml z8530book.xml mcabook.xml videobook.xml \
procfs-guide.xml writing_usb_driver.xml \
kernel-api.xml filesystems.xml lsm.xml usb.xml \
gadget.xml libata.xml mtdnand.xml librs.xml rapidio.xml \
genericirq.xml s390-drivers.xml
genericirq.xml s390-drivers.xml uio-howto.xml

###
# The build process is as follows (targets):
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90 changes: 32 additions & 58 deletions trunk/Documentation/DocBook/uio-howto.tmpl
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Expand Up @@ -29,6 +29,12 @@
</abstract>

<revhistory>
<revision>
<revnumber>0.4</revnumber>
<date>2007-11-26</date>
<authorinitials>hjk</authorinitials>
<revremark>Removed section about uio_dummy.</revremark>
</revision>
<revision>
<revnumber>0.3</revnumber>
<date>2007-04-29</date>
Expand Down Expand Up @@ -94,6 +100,26 @@ interested in translating it, please email me
user space. This simplifies development and reduces the risk of
serious bugs within a kernel module.
</para>
<para>
Please note that UIO is not an universal driver interface. Devices
that are already handled well by other kernel subsystems (like
networking or serial or USB) are no candidates for an UIO driver.
Hardware that is ideally suited for an UIO driver fulfills all of
the following:
</para>
<itemizedlist>
<listitem>
<para>The device has memory that can be mapped. The device can be
controlled completely by writing to this memory.</para>
</listitem>
<listitem>
<para>The device usually generates interrupts.</para>
</listitem>
<listitem>
<para>The device does not fit into one of the standard kernel
subsystems.</para>
</listitem>
</itemizedlist>
</sect1>

<sect1 id="thanks">
Expand Down Expand Up @@ -174,8 +200,9 @@ interested in translating it, please email me
For cards that don't generate interrupts but need to be
polled, there is the possibility to set up a timer that
triggers the interrupt handler at configurable time intervals.
See <filename>drivers/uio/uio_dummy.c</filename> for an
example of this technique.
This interrupt simulation is done by calling
<function>uio_event_notify()</function>
from the timer's event handler.
</para>

<para>
Expand Down Expand Up @@ -263,63 +290,11 @@ offset = N * getpagesize();
</sect1>
</chapter>

<chapter id="using-uio_dummy" xreflabel="Using uio_dummy">
<?dbhtml filename="using-uio_dummy.html"?>
<title>Using uio_dummy</title>
<para>
Well, there is no real use for uio_dummy. Its only purpose is
to test most parts of the UIO system (everything except
hardware interrupts), and to serve as an example for the
kernel module that you will have to write yourself.
</para>

<sect1 id="what_uio_dummy_does">
<title>What uio_dummy does</title>
<para>
The kernel module <filename>uio_dummy.ko</filename> creates a
device that uses a timer to generate periodic interrupts. The
interrupt handler does nothing but increment a counter. The
driver adds two custom attributes, <varname>count</varname>
and <varname>freq</varname>, that appear under
<filename>/sys/devices/platform/uio_dummy/</filename>.
</para>

<para>
The attribute <varname>count</varname> can be read and
written. The associated file
<filename>/sys/devices/platform/uio_dummy/count</filename>
appears as a normal text file and contains the total number of
timer interrupts. If you look at it (e.g. using
<function>cat</function>), you'll notice it is slowly counting
up.
</para>

<para>
The attribute <varname>freq</varname> can be read and written.
The content of
<filename>/sys/devices/platform/uio_dummy/freq</filename>
represents the number of system timer ticks between two timer
interrupts. The default value of <varname>freq</varname> is
the value of the kernel variable <varname>HZ</varname>, which
gives you an interval of one second. Lower values will
increase the frequency. Try the following:
</para>
<programlisting format="linespecific">
cd /sys/devices/platform/uio_dummy/
echo 100 > freq
</programlisting>
<para>
Use <function>cat count</function> to see how the interrupt
frequency changes.
</para>
</sect1>
</chapter>

<chapter id="custom_kernel_module" xreflabel="Writing your own kernel module">
<?dbhtml filename="custom_kernel_module.html"?>
<title>Writing your own kernel module</title>
<para>
Please have a look at <filename>uio_dummy.c</filename> as an
Please have a look at <filename>uio_cif.c</filename> as an
example. The following paragraphs explain the different
sections of this file.
</para>
Expand Down Expand Up @@ -354,9 +329,8 @@ See the description below for details.
interrupt, it's your modules task to determine the irq number during
initialization. If you don't have a hardware generated interrupt but
want to trigger the interrupt handler in some other way, set
<varname>irq</varname> to <varname>UIO_IRQ_CUSTOM</varname>. The
uio_dummy module does this as it triggers the event mechanism in a timer
routine. If you had no interrupt at all, you could set
<varname>irq</varname> to <varname>UIO_IRQ_CUSTOM</varname>.
If you had no interrupt at all, you could set
<varname>irq</varname> to <varname>UIO_IRQ_NONE</varname>, though this
rarely makes sense.
</para></listitem>
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39 changes: 39 additions & 0 deletions trunk/Documentation/namespaces/compatibility-list.txt
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Namespaces compatibility list

This document contains the information about the problems user
may have when creating tasks living in different namespaces.

Here's the summary. This matrix shows the known problems, that
occur when tasks share some namespace (the columns) while living
in different other namespaces (the rows):

UTS IPC VFS PID User Net
UTS X
IPC X 1
VFS X
PID 1 1 X
User 2 2 X
Net X

1. Both the IPC and the PID namespaces provide IDs to address
object inside the kernel. E.g. semaphore with IPCID or
process group with pid.

In both cases, tasks shouldn't try exposing this ID to some
other task living in a different namespace via a shared filesystem
or IPC shmem/message. The fact is that this ID is only valid
within the namespace it was obtained in and may refer to some
other object in another namespace.

2. Intentionally, two equal user IDs in different user namespaces
should not be equal from the VFS point of view. In other
words, user 10 in one user namespace shouldn't have the same
access permissions to files, belonging to user 10 in another
namespace.

The same is true for the IPC namespaces being shared - two users
from different user namespaces should not access the same IPC objects
even having equal UIDs.

But currently this is not so.

8 changes: 8 additions & 0 deletions trunk/Documentation/tty.txt
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Expand Up @@ -132,6 +132,14 @@ set_termios() Notify the tty driver that the device's termios
tty->termios. Previous settings should be passed in
the "old" argument.

The API is defined such that the driver should return
the actual modes selected. This means that the
driver function is responsible for modifying any
bits in the request it cannot fulfill to indicate
the actual modes being used. A device with no
hardware capability for change (eg a USB dongle or
virtual port) can provide NULL for this method.

throttle() Notify the tty driver that input buffers for the
line discipline are close to full, and it should
somehow signal that no more characters should be
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8 changes: 8 additions & 0 deletions trunk/Documentation/usb/power-management.txt
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Expand Up @@ -278,6 +278,14 @@ optional. The methods' jobs are quite simple:
(although the interfaces will be in the same altsettings as
before the suspend).

If the device is disconnected or powered down while it is suspended,
the disconnect method will be called instead of the resume or
reset_resume method. This is also quite likely to happen when
waking up from hibernation, as many systems do not maintain suspend
current to the USB host controllers during hibernation. (It's
possible to work around the hibernation-forces-disconnect problem by
using the USB Persist facility.)

The reset_resume method is used by the USB Persist facility (see
Documentation/usb/persist.txt) and it can also be used under certain
circumstances when CONFIG_USB_PERSIST is not enabled. Currently, if a
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29 changes: 29 additions & 0 deletions trunk/Documentation/x86_64/uefi.txt
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General note on [U]EFI x86_64 support
-------------------------------------

The nomenclature EFI and UEFI are used interchangeably in this document.

Although the tools below are _not_ needed for building the kernel,
the needed bootloader support and associated tools for x86_64 platforms
with EFI firmware and specifications are listed below.

1. UEFI specification: http://www.uefi.org

2. Booting Linux kernel on UEFI x86_64 platform requires bootloader
support. Elilo with x86_64 support can be used.

3. x86_64 platform with EFI/UEFI firmware.

Mechanics:
---------
- Build the kernel with the following configuration.
CONFIG_FB_EFI=y
CONFIG_FRAMEBUFFER_CONSOLE=y
- Create a VFAT partition on the disk
- Copy the following to the VFAT partition:
elilo bootloader with x86_64 support, elilo configuration file,
kernel image built in first step and corresponding
initrd. Instructions on building elilo and its dependencies
can be found in the elilo sourceforge project.
- Boot to EFI shell and invoke elilo choosing the kernel image built
in first step.
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