May 2012 - kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

UPS driver
by Peter Senna Tschudin May 6, 2012

May 6, 2012

Dear list, Is there a specific mailing list for POWER SUPPLY CLASS/SUBSYSTEM and DRIVERS? I'm writing a driver for the UPS: http://www.sms.com.br/produtos/Nobreak-SMS/Manager-III-Senoidal The communication protocol between PC and UPS is simple and I did userspace tool for that. https://github.com/petersenna/nobreakSMS/blob/master/userland/nobreakSMS.c Now I'm writing the Linux driver for it. I want to present the UPS as AC+Battery to the user. But when using POWER_SUPPLY_TYPE_UPS (defined at: include/linux/power_supply.h), gnome-power* do not present the UPS to the user even the values being available though /sys. It this a bug for gnome-power*? Or is it expected to not present UPS information to the user as AC+Battery? About the battery type should I make a patch for adding lead acid battery type? This is still very common as battery type for UPS. Anything like: --//-- diff -Nrp a/power_supply.h b/power_supply.h *** a/power_supply.h 2012-05-05 21:57:30.136563463 -0300 --- b/power_supply.h 2012-05-05 21:58:53.293402380 -0300 *************** enum { *** 63,68 **** --- 63,69 ---- POWER_SUPPLY_TECHNOLOGY_LiFe, POWER_SUPPLY_TECHNOLOGY_NiCd, POWER_SUPPLY_TECHNOLOGY_LiMn, + POWER_SUPPLY_TECHNOLOGY_PbH2SO4, }; enum { --//-- Any idea if the maintainers are accepting drivers for devices like this UPS? Kind Regards, Peter -- Peter Senna Tschudin peter.senna(a)gmail.com gpg id: 48274C36

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Some questions about boot memory
by loody May 4, 2012

May 4, 2012

hi all: I have some question about the relationship between page table creation and bootmemery allocation. bootmemory allocation use 1-bit to declare this page is used or not. Does that mean when a new page table is creating, it will reference the bits of bootmap and add dirty flag on the page of the page table created? -- Thanks a lot

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Problem of workqueue
by 夏业添 May 4, 2012

May 4, 2012

Hi, I want to use workqueue in my irq handler. Some materials say that I can use INIT_WORK( &work, function, &data ); to initialize work, whose type is struct work_struct, and data is something should be passed to function. however, it seems that now the macro INIT_WORK() only accept two parameters:&work and function. My problem is how to pass data to the function and why they change that macro? Thanks!

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Logging sensitive information from kernel (while atomic and uninterrupted)
by Panagiotis Sakkos May 4, 2012

May 4, 2012

Hi again, I would like to ask you the possible ways of logging information from the kernel, without the messages being intercepted from dmesg. Also please note that my implementation uses the kprobes API, so in my probes I am atomic and uninterrupted. * printk sends the logs to the kernel ring buffer, so dmesg will always see them. Hence, printk-ing is not a solution. * Logging to a unix socket (i.e. /dev/log) didn't work (check "Crash when sending a lot of messages through a unix socket" thread). * proc filesystem, I am not sure, but I believe that is not suitable for logging information. It is more for kernel information exposing. Any other ideas? My problem is that I log sensitive data and any unprivileged user can run dmesg and see the sensitive logs. Thank you in advance for your time, Panos -- http://www.cern.ch/psakkos

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kernelnewbies
by yuwenjun_maillist May 4, 2012

May 4, 2012

echo subscribe kernelnewbies | mail listar(a)nl.linux.org 2012-05-04 yuwenjun_maillist

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kernelnewbies
by yuwenjun_maillist May 4, 2012

May 4, 2012

:0 * ^List-Id:.*kernelnewbies.kernelnewbies.org Mail/kernelnewbies 2012-05-04 yuwenjun_maillist

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Crash when sending a lot of messages through a unix socket
by Panagiotis Sakkos May 3, 2012

May 3, 2012

Hi, I am trying to log information from within the kernel with the use of a unix socket (/dev/log). My code is a kprobe handler, so while executing I am atomic and uninterrupted. The crashes begin when I do stress tests against my module, so i.e. more than 50 logs per second. The crash messages I get every time are different (from NULL reference, unable to handle page request etc), so I suppose that something is overwritten and this leads to the crash. I don't want to post the code here because it ~100 LOC but these are my steps: Initialization: call sock_create_kern, with PF_UNIX, SOCK_DGRAM, 0 and the address of my socket, then I memset to 0 my sockaddr_un variable and then I set its sun_family to PF_UNIX and copy the "/dev/log" string to sun_path Logging: I have the message that I want to log in variable called buffer and its length in variable called message_length, I set the msg_name of the msghdr to the address of my sockaddr_un variable, than the msn_namelen to sizeof(sockadrr_un), the msg_iov to an iovec variable which contains the buffer and the message_length values, msg_iovlen to 1 and msg_control, msg_controllen to 0. Then I set the fs to KERNEL_DS, call sock_sendmsg with parameters my socket, the address of my msghdr and the message_length and then I restore the fs that there was before setting it to KERNEL_DS. Please note that my socket, sockadd_un and my buffer are static variables. Also I always use the socket which is initialized once in the Initialization state (function). Do you see any "bad practice" or something that could lead to crashes when stressing with a lot of messages the socket? Thank you in advance! Panos -- http://www.cern.ch/psakkos

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about kmemtrace-user program
by loody May 3, 2012

May 3, 2012

hi all: from below thread, http://www.kerneltrap.org/mailarchive/linux-kernel/2009/12/24/4522989 it seems kmemtrace-user, http://repo.or.cz/w/kmemtrace-user.git, cannot work on current kernel. if it is the truth, is there any other user program I can use for replacing kmemtrace-user. -- Regards,

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Writing a single buffer in kernel ring buffer take 6-8 ms
by Chetan Nanda May 3, 2012

May 3, 2012

Hi, We are working on ARM based SOC. Currently we are implementing a efficient tracing mechanism to logs messages from a dedicated MCU. For this, we share a circular buffer between ARM and MCU and messages stored in the buffer will be put into kernel ring-buffer and then output via dmesg call. Strangely wringing a single log message in the kernel ring-buffer cost around 6-8ms. Please help to confirm this, or we are doing something wrong. Thanks, Chetan Nanda

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RE: Crash when sending a lot of messages through a unix socket
by Pranay Kumar Srivastava May 2, 2012

May 2, 2012

You mentioned your code is atomic. Are you certain that you can do a sock_sendmsg from a non process context? I believe you can't do that from a non process context cuz sock_sendmsg-->udp_sendmsg for DGRAM and i think that assumes you are in process context. ________________________________________ From: kernelnewbies-bounces(a)kernelnewbies.org [kernelnewbies-bounces(a)kernelnewbies.org] On Behalf Of kernelnewbies-request(a)kernelnewbies.org [kernelnewbies-request(a)kernelnewbies.org] Sent: Wednesday, May 02, 2012 9:30 PM To: kernelnewbies(a)kernelnewbies.org Subject: Kernelnewbies Digest, Vol 18, Issue 2 Send Kernelnewbies mailing list submissions to kernelnewbies(a)kernelnewbies.org To subscribe or unsubscribe via the World Wide Web, visit http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies or, via email, send a message with subject or body 'help' to kernelnewbies-request(a)kernelnewbies.org You can reach the person managing the list at kernelnewbies-owner(a)kernelnewbies.org When replying, please edit your Subject line so it is more specific than "Re: Contents of Kernelnewbies digest..." Today's Topics: 1. please report distros with CONFIG_DYNAMIC_DEBUG, using ddebug_query= boot param (Jim Cromie) 2. Re: immutable wiki? (michi1(a)michaelblizek.twilightparadox.com) 3. Re: immutable wiki? (Bill Traynor) 4. Crash when sending a lot of messages through a unix socket (Panagiotis Sakkos) ---------------------------------------------------------------------- Message: 1 Date: Tue, 1 May 2012 12:36:04 -0600 From: Jim Cromie <jim.cromie(a)gmail.com> Subject: please report distros with CONFIG_DYNAMIC_DEBUG, using ddebug_query= boot param To: kernelnewbies <kernelnewbies(a)kernelnewbies.org> Message-ID: <CAJfuBxw8aYimAU7kO42vh_e-zZBNSkw9Hd8Dx2tFCOWL4ueVgQ(a)mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1 hi all, Ive been asked whether ddebug_query= boot param is used in any distros, I think the question seeks to determine a good deprecation schedule for it (its been obsoleted by dyndbg= in driver-core-next) Would you all be so kind as to check your favorite distros, and report the ones that have one or both ? Ubuntu 12.04 LTS lacks it: jimc@chumly:~/projects/lx/linux-2.6$ grep DYNAMIC_DEBUG /boot/config* /boot/config-3.0.0-17-generic:# CONFIG_DYNAMIC_DEBUG is not set /boot/config-3.2.0-24-generic:# CONFIG_DYNAMIC_DEBUG is not set Voyage linux also lacks it, (also debian based) Fedora-16 has config option: $ uname -a Linux groucho.jimc.earth 3.3.2-6.fc16.x86_64 #1 SMP Sat Apr 21 12:43:20 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux $ grep DYNAMIC_DEBUG /boot/config-3.3.* /boot/config-3.3.1-5.fc16.x86_64:CONFIG_DYNAMIC_DEBUG=y /boot/config-3.3.2-1.fc16.x86_64:CONFIG_DYNAMIC_DEBUG=y /boot/config-3.3.2-6.fc16.x86_64:CONFIG_DYNAMIC_DEBUG=y but its not used by default. I have modified my grub defaults: $ grep ddebug_query /etc/default/grub GRUB_CMDLINE_LINUX='quiet rhgb loglevel=8 ddebug_query="module params +p" dynamic_debug.verbose=1 nouveau.dyndbg nouveau.force_post=1 it87.dyndbg=+p nouveau.perflvl_wr=7777' FYI, the above usage will eventually be unsupported, it can be replaced in driver-core-next by either of: dyndbg="module params +p" params.dyndbg=+p params.dyndbg # defaults to +p the 2nd, 3rd forms also work for loadable modules (though params isnt one of them) thanks in advance Jim ------------------------------ Message: 2 Date: Wed, 2 May 2012 12:52:38 +0200 From: michi1(a)michaelblizek.twilightparadox.com Subject: Re: immutable wiki? To: Bill Traynor <wmat(a)alphatroop.com> Cc: kernelnewbies(a)kernelnewbies.org Message-ID: <20120502105237.GA2229@grml> Content-Type: text/plain; charset=us-ascii Hi! On 09:29 Tue 01 May , Bill Traynor wrote: > I have an Editor account for the kernelnewbies.org wiki, but all pages > are currently immutable. Was the wiki made read-only at some point? You must be on http://kernelnewbies.org/EditorsGroup to make changes. This was made for spam procection. Everybody who is on the list can add you. What is your username in the wiki? -Michi -- programing a layer 3+4 network protocol for mesh networks see http://michaelblizek.twilightparadox.com ------------------------------ Message: 3 Date: Wed, 2 May 2012 08:06:36 -0400 From: Bill Traynor <wmat(a)alphatroop.com> Subject: Re: immutable wiki? To: michi1(a)michaelblizek.twilightparadox.com Cc: kernelnewbies(a)kernelnewbies.org Message-ID: <CAGfZjq69kO91rbiG8R5jTUmRDq3ZJRjp_oTLqS8wji1M%3D1NJ-Q(a)mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1 On Wed, May 2, 2012 at 6:52 AM, <michi1(a)michaelblizek.twilightparadox.com> wrote: > Hi! > > On 09:29 Tue 01 May ? ? , Bill Traynor wrote: >> I have an Editor account for the kernelnewbies.org wiki, but all pages >> are currently immutable. ?Was the wiki made read-only at some point? > > You must be on http://kernelnewbies.org/EditorsGroup to make changes. This > was made for spam procection. Everybody who is on the list can add you. What > is your username in the wiki? Thanks Michael, Rik already fixed it for me. > > ? ? ? ?-Michi > -- > programing a layer 3+4 network protocol for mesh networks > see http://michaelblizek.twilightparadox.com ------------------------------ Message: 4 Date: Wed, 2 May 2012 13:43:41 +0000 From: Panagiotis Sakkos <panos.sakkos(a)cern.ch> Subject: Crash when sending a lot of messages through a unix socket To: "kernelnewbies(a)kernelnewbies.org" <kernelnewbies(a)kernelnewbies.org> Message-ID: <A1F86B12A2E22C4CB3164ECFFD1C54DB08EC9407(a)PLOXCHG03.cern.ch> Keywords: CERN SpamKiller Note: -50 Content-Type: text/plain; charset="iso-8859-1" Hi, I am trying to log information from within the kernel with the use of a unix socket (/dev/log). My code is a kprobe handler, so while executing I am atomic and uninterrupted. The crashes begin when I do stress tests against my module, so i.e. more than 50 logs per second. The crash messages I get every time are different (from NULL reference, unable to handle page request etc), so I suppose that something is overwritten and this leads to the crash. I don't want to post the code here because it ~100 LOC but these are my steps: Initialization: call sock_create_kern, with PF_UNIX, SOCK_DGRAM, 0 and the address of my socket, then I memset to 0 my sockaddr_un variable and then I set its sun_family to PF_UNIX and copy the "/dev/log" string to sun_path Logging: I have the message that I want to log in variable called buffer and its length in variable called message_length, I set the msg_name of the msghdr to the address of my sockaddr_un variable, than the msn_namelen to sizeof(sockadrr_un), the msg_iov to an iovec variable which contains the buffer and the message_length values, msg_iovlen to 1 and msg_control, msg_controllen to 0. Then I set the fs to KERNEL_DS, call sock_sendmsg with parameters my socket, the address of my msghdr and the message_length and then I restore the fs that there was before setting it to KERNEL_DS. Please note that my socket, sockadd_un and my buffer are static variables. Also I always use the socket which is initialized once in the Initialization state (function). Do you see any "bad practice" or something that could lead to crashes when stressing with a lot of messages the socket? Thank you in advance! Panos -- http://www.cern.ch/psakkos

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