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how to deal with page
by 于运超 March 7, 2014

March 7, 2014

Hi. nowdays i am studing Transparent encryption in linux system. when reading file needs do_generic_file_read function decrpty file. but in do_generic_file_read Physical data using struct page ,how did i use page decrpty.

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usb drivers
by Kalyan Kodamagula March 6, 2014

March 6, 2014

Hi, Iam new to this ML,I need info regarding Usb device drivers.I had learned Lnx device drivers and having knowledge on USB Host driver(highlevel). I had seen probe/read/write functions of a driver.As there is no need to write drivers from scratch,we can gain knowledge by fixing some bugs in the driver. Can some one please give me links/doc to see the bugs and related fixes of USB drivers. BR.

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Assigning an unique name to USB CDC device in /dev
by Srinivas Ganji March 5, 2014

March 5, 2014

Dear All, We have a USB CDC device which we are connecting it to the Ubuntu system. Then, we are accessing the device using an application by opening the device with /dev/ttyACM0 node. The system may have multiple USB CDC devices already connected before connecting my device, sometimes. In such cases, my application fails to open the device, because, this time the assigned node is other than /dev/ttyAMC0, but in my application the device node is /dev/ttyAMC0 only. Due to these reasons, I want to assign my own device node in the /dev directory like /dev/mydev. This will enable my application to identify my device very easily. The requirement is same as described in the link - http://marc.info/?l=linux-usb&m=130216901901572&w=2 The answer is available at http://marc.info/?l=linux-usb&m=130217684009490&w=2 I have tried in different ways as I have also looked at the following sources. But, still, there is NO luck. When I insert another USB CDC device, it got /dev/ttyACM0 instead of getting ttyACM1. http://www.reactivated.net/writing_udev_rules.html https://www.kernel.org/pub/linux/utils/kernel/hotplug/udev/udev.html http://unix.stackexchange.com/questions/77476/point-usb-phone-to-specific-d… https://www.pjrc.com/teensy/49-teensy.rules The kernel version and distribution details are as follows. Kernel Version --- 3.5.0-17-generic Distribution details are as follows. RELEASE=14 CODENAME=nadia EDITION="MATE 64-bit" DESCRIPTION="Linux Mint 14 Nadia" I have created a file, named 11-ttyACM.rules, under /etc/udev/rules.d directory. The contents of the file as follows. KERNEL=="ttyAMC0", SUBSYSTEM=="tty", ATTRS{serial}=="__0X00124B000148CC78", SYMLINK+="mydev" I got the above information from the following command udevadm info -q all -n /dev/ttyACM0 --attribute-walk This is what I did. But, no luck. If I insert a different serial numbered device, then it is assigning ttyACM0 to that device. But, after this udev rule, it should not assign, I think. Please someone, who already used/knows udev rules, suggest me. Thanks. Regards, Srinivas.

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Re: My Kernel bug is celebrating 2 years. Can you help me fix it?
by Peter Senna Tschudin March 5, 2014

March 5, 2014

On Mar 5, 2014 9:27 AM, "walter harms" <wharms(a)bfs.de> wrote: > > > > Am 04.03.2014 22:26, schrieb Peter Senna Tschudin: > > I have reported a bug more than two years ago and it is still > > affecting me. The bug report gives some information: > > > > https://bugzilla.redhat.com/show_bug.cgi?id=787299 > > > > I have tried basic debug instructions from: > > https://www.kernel.org/doc/Documentation/power/basic-pm-debugging.txt > > > > And everything works as expected when: > > # echo freeze > /sys/power/state > > # echo disk > /sys/power/state > > > > I have asked for help for fixing it: > > https://lkml.org/lkml/2013/11/1/186 > > > > But I don't have a serial port. How can I debug this issue without a > > "real" serial port? Or what else can I try? > You need to create a kernel with networksupport, > setup "netconsole" you need a second computer to receive the issues. I have tried, and it does not work. The kernel do not start running properly after resume, so there is no network... > > > >How can I explore the hint > > about the problem only happening with VT-d enabled in BIOS? How can I > > explore the hint about the problem not happening if the option > > nox2apic is passed to the Kernel? > > never heard about that until now, obviously there is a bug in several > acpi's that can be triggered. If your systems works with nox2apic > as bootparameter you should be happy since a workaround is available. > Information about it is used can be find here: > http://lxr.free-electrons.com/ident?a=microblaze;i=nox2apic Sorry, I'm not happy with the workaround, I want it to work. Thank you for the link, I'll check it. > > re, > wh > > > > Thank you, > > > > Peter > > > > P.S Yes, it works on Windows. > >

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How to fix Fn key on laptops.
by Prakash Shiva March 5, 2014

March 5, 2014

I see there is no support to Fn key on few laptops. I want to develop a driver to include Fn key and contribute to opensource. I am using SONY VAIO laptop running ubuntu 12.03(kernel version: 3.0.51). Question no 1: How do i find keyboard source code for my laptop(SONY VAIO VPCEG25N)? I see there is 4 entires in source code for keyboard.c : a. drivers/input/keyboard/spear-keyboard.c<http://lxr.linux.no/linux+*/drivers/input/keyboard/spear-keyboard.c> b. drivers/s390/char/keyboard.c<http://lxr.linux.no/linux+*/drivers/s390/char/keyboard.c> c. drivers/tty/vt/keyboard.c<http://lxr.linux.no/linux+*/drivers/tty/vt/keyboard.c> d. kernel/debug/kdb/kdb_keyboard.c<http://lxr.linux.no/linux+*/kernel/debug/kdb/kdb_keyboard.c> Question no 2: Is it possible to tap scancode of Fn key using the source code? Thanks and I respect your time. Regards Prakash S

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Good kernel kick-start
by Mallesh Koujalagi March 5, 2014

March 5, 2014

http://www.osdever.net/bkerndev/index.php

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Re: [Printing-architecture] Google Summer of Code 2014 - IPP-over-USB printer support - Joint project idea for OpenPrinting and the kernel
by Michael Sweet March 5, 2014

March 5, 2014

Carlos, On Mar 4, 2014, at 5:28 PM, Carlos Rimola <crimola(a)gmail.com> wrote: > Hello All, > > I have a couple of "simple" follow-up questions on IPP USB (IPP-over-USB) "Host device" support: > > Is IPP USB designed to support connecting and printing from a device like a tablet or smartphone (e.g., iPad, iPhone, Etc.) directly connected to a printer over USB? Honestly, no. Who would want to tether their mobile device to print something? Wi-Fi (and soon Wi-Fi Direct) offer ways of printing from mobile devices to these same printers (most of which already have Wi-Fi and/or Ethernet interfaces...) > ... > Or is IPP USB designed only for Hosts like Linux or Mac acting as print servers/gateways for these, and other, devices? It is mainly for existing desktop/portable/personal server/NAS/other-embedded usage that currently relies on the old USB printer class protocol and printer drivers. The (hopefully not too) long term goal is to eliminate the need for printer drivers, much as today you don't need a special driver for a USB keyboard or mouse. (and like keyboards and mice you might still get some software from the vendor to provide additional functionality, but generally you'll be able to just plug a printer in and print something without installing extra software...) For IPP USB in particular I think we'll see adoption by NAS and other network boxes that already provide primitive printer sharing. _________________________________________________________ Michael Sweet, Senior Printing System Engineer, PWG Chair

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Re: [Printing-architecture] Google Summer of Code 2014 - IPP-over-USB printer support - Joint project idea for OpenPrinting and the kernel
by Michael Sweet March 4, 2014

March 4, 2014

Carlos, Any Mac running OS X 10.9 supports IPP USB; note that we have a bunch of pending bug fixes (sorry, can't say when the fixes will be released...) that address issues found in testing with multiple vendors' implementations of IPP USB, but the current 10.9.2 will work with all of the HP printers mentioned below. On Feb 27, 2014, at 2:23 PM, Carlos Rimola <crimola(a)gmail.com> wrote: > Michael, > > Thanks for the comprehensive response to my questions on IPP USB and confirming my assumptions. > > The only remaining question I have for the list at this time is - are there any Hosts, including model, OS and OS version (or other S/W requirements), presently available on the market (or otherwise) which support IPP USB as per the Specification? > > Thanks again, > > Carlos Rimola > > > On Thu, Feb 27, 2014 at 7:37 AM, Michael Sweet <msweet(a)apple.com> wrote: > Carlos, > > On Feb 26, 2014, at 9:33 PM, Carlos Rimola <crimola(a)gmail.com> wrote: >> Hi All, >> >> I have some quick and general questions regarding IPP over USB ("IPP USB" for short). Some are related to Till's proposed project "Google Summer of Code 2014 - IPP-over-USB printer support". Any help and feedback will be greatly welcomed. I should mention that I am in favor of the proposed project for this event. >> >> Assumptions (please confirm or correct): >> >> 1) This first one may be obvious but to be sure - I am assuming that we are referring to IPP USB as defined in the "USB Print Interface Class IPP Protocol Specification Revision 1.0" dated 12/5/2012 and published by USB-IF and authored by HP's Smith Kennedy and Andrew R. Mitchell. I'll refer to it as the "IPP USB Spec". >> > Correct. >> 2) As I understand the IPP USB Spec, there is NO network interface, NOR TCP/IP involved. The Communication Protocol to be used between Host and Device (Printer) is purely HTTP + IPP directly over USB. A place where this is noted is section 6.2 - "HTTP Headers" which states the following: >> >> Since there is NO network interface connection, NO DNS hostnames or IP addresses, and NO TCP port numbers associated with USB connection, the requirements of the HTTP Host field is addressed by requiring that the value of this header MUST be "localhost". >> >> Please correct me if I am wrong on either of these assumptions. >> > > Correct (a port number can be passed by the "client" over USB to allow gateways/proxies to work...) >> Questions: >> >> 1) I know the Spec is already cast in stone but I would like to understand what function HTTP serves and if it is only used for identifying "Host: localhost" and the "/ipp/printer" path? In other words, could pure IPP Requests/Responses and IPP expected format "Print Data" have sufficed? > > While you might get away with that for simple IPP messages, that wouldn't work for document data since IPP by itself has no framing or other niceties - you'd never know when the data ended. > > Also, the HTTP portion is used for the embedded web server, doing firmware updates, and so forth. >> >> 2) Section 3.2 "Interface Set" paragraph 2 states that "All IPP USB capable Print class interfaces provided by a device MUST be functionally equal from an IPP operation or HTTP perspective. In other words, any IPP operation or resource path that is valid over one IPP USB interface MUST be reachable via any and all of the IPP USB interfaces." >> >> Does this imply that, for example, a Request from the host can be sent over one interface (I/F #1) and the response received over a different interface (e.g., I/F #2)? >> > No, each interface is an independent channel to the printer. > > The reason for this requirement is to prevent having an IPP USB endpoint just for printing, and another just for scanning, and so forth. Effectively IPP USB defines an interface protocol that allows arbitrary HTTP and IPP requests to be performed. >> 3) The last question is much simpler but would be helpful to an implementor - what specific printers (manufacturer, line and model) on the market support IPP USB? I have seen references to HP Photosmart and OfficeJet but no model given. Similarly, what Host(s) on the market, including OS and version, support the IPP USB protocol with these Printers? >> > Here is the latest list we have from HP: > > Deskjet 3520 > Envy 120 > Envy 4500 > Envy 5530 > Officejet 3620 > Officejet 4630 > Officejet 7610 > Officejet Pro 276 MFP > Officejet Pro X576 dw > Photosmart 5520 > Photosmart 6520 > Photosmart 7520 > > I know of four other manufacturers that either have shipping products or will soon be shipping - will post here when I can do so publicly... > > _________________________________________________________ > Michael Sweet, Senior Printing System Engineer, PWG Chair > > _________________________________________________________ Michael Sweet, Senior Printing System Engineer, PWG Chair

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module usage count
by J.Hwan Kim March 4, 2014

March 4, 2014

Hi, everyone When I use /proc file system in communicating between kernel and user space, is the usage count of moudule automatically incremented or decremented? I register proc file via create_proc_entry() and use .open, .close and .mmap not using .read and .write function. Please give me any hint.. Thanks in advance Best Regards, J.Hwan Kim

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Device Tree support for x86_64 kernel? Unresolved symbol apic_force_enable
by Bob Paauwe March 3, 2014

March 3, 2014

Background: I'm working on a project that needs device tree like capability. Using the device tree OF driver works well and I don't want to create something that closely duplicates that functionality. When building a 32bit kernel, all works fine. However when building a 64bit kernel, the linking stage fails with an unresolved symbol: apic_force_enable This symbol is getting called from arch/x86/kernel/devicetree.c and is defined in arch/x86/kernel/apic/apic.c but only when !CONFIG_X86_64 I see two possible fixes but as I'm unfamiliar with this area of the kernel I don't know which would be a better choice. 1) in arch/x86/kernel/apic/apic.c, define the apic_force_enable() function in the X86_64 bit path and have it return 0. Something like: int __init apic_force_enable(unsigned long addr) { return 0; } 2) wrap the call to apic_force_enable with a #ifndef CONFIG_X86_64 in devicetree.c. Something like : #ifndef CONFIG_X86_64 if (apic_force_enable(r.start)) return; #else return; #endif I've been using #1 successfully in my development and it seems like it would be the best choice long term. I'm looking for some validation that this makes sense and if so, I'll submit a patch to lkm with the fix.

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