November 2014 - kernelnewbies@kernelnewbies.org

from WHERE platform driver's probe is called?
by Sunil Shahu Nov. 22, 2014

Nov. 22, 2014

Hello, I am looking into platform driver and devices and understood HOW platform driver's probe is called from kernel doc and following forum.http://comments.gmane.org/gmane.linux.kernel.kernelnewbies/37050 For further information I went through code in platform_driver_register() and got lost. I looked web but could not find substantiation information. I am still not able to locate from WHERE this probe function is called and WHO calls it?Can someone please point to source code or some other document related to this? Thanks,Sunil.

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VLAN tagged packets received by application are corrupted
by Amit Agarwal Nov. 21, 2014

Nov. 21, 2014

Hi all, I have query on vlan tagged packets received by network interface. Problem: I have application which would receive all packets on the interface and process them ( this could be including vlan tagged packets). However when the 8021q (vlan) module is not loaded and the appropriate interfaces for all the IDs are not created I see that the application is not able to decode them. When we capture with tcpdump/tshark/wireshark as well we see that the packets are not correctly displayed. The Ethernet header type itself is not correctly identified and thus the rest of the packet cannot be decoded. What could be causing this and is there a way to fix this? -- Thanks, -aka

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Userspace agent crash and kernel module
by Kevin Wilson Nov. 21, 2014

Nov. 21, 2014

Hi, I want to write a kernel module which interacts with a userspace daemon. There are cases when the userspace daemon can terminate by some signals. There are also cases where the userspace daemon can crash (in some abnormal cases). Is there a way that the kernel module will be aware of such userspace agent crash, in order to reset its state ? Regards, Kevin

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Devres
by Raphael Philipe Nov. 21, 2014

Nov. 21, 2014

I have a device driver that requests a lot o memory regions with ioremap and request_mem_region. Today I came across devres. I would like to known your oppinion regarding it? If you don't know it, take a look here. http://haifux.org/lectures/323/haifux-devres.pdf It seems like a garbage collector for Linux Kernel. Do you agree? Regards,

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the task_struct
by ♂~~☆ Nov. 21, 2014

Nov. 21, 2014

Hi,allThese days i tried to study the structure task_truct in linux kernel 2.65.32,but the member of the struct is so gigantic.What' more,many materials are just to list the struct,but not show the meaning of the members in task_struct,and many books of kernel study also do not explian the use of the members.But,i want to understand the structure deeply.Now,i am in a big trouble,and i need help from you.Anybody who can give me a hand? thanks! Hw

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Why each time of kernel compilation must be done completely?
by 秦弋戈 Nov. 21, 2014

Nov. 21, 2014

Hi, This problem has puzzled me for a long time. A normal C make file could parse the reliance and just regenerate the modified source file. But each time when I modified the kernel and recompile it, it does a complete compilation, no matter whether make mrproper is used or not. It's quite time consuming and inefficient. So why kernel make file couldn't do what a normal C make file could do? Or maybe it could but I got something wrong? If a complete compilation is inevitable, how to make it faster? I only know the -jX option. Best regards Michael

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ABI choice in adding new syscall
by Marcelo Silva Freitas Nov. 20, 2014

Nov. 20, 2014

Hi, I am studing how to add new syscall to the kernel. When editing the file syscall_64.tlb there are 3 choices for the ABI: 64, common, x32 I have read about and I don't found clearly the meaning and effect of 'common' choice. In what imply this choice? Thanks, Marcelo.

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tcp retransmission concept.
by Varun Sharma Nov. 20, 2014

Nov. 20, 2014

Hi, Is any one know how tcp retransmission works inside kernel ? regards varun

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dm-verity and backing_dev_info
by David Legault Nov. 20, 2014

Nov. 20, 2014

Hello, I'm working on a project where I use the dm-verity data mapper on top of a regular emmc device block. The intent is that once the verity device mapper is verified successfully (top level hash verification) on top of the emmc block device and mounted to a filesystem (ext4) that the filesystem is trusted in some way and store that bit of information somewhere in kernel space. My original thought was to think that the new dm-verity block device would of had it's own backing_dev_info structure on which I would of added a new capability called BDI_CAP_TRUSTED which then could of been used for additional checks to see if files come from a trusted file system. I instrumented the kernel exec command to verify if the backing_dev_info was different depending on if a file same from a dm-verity mounted filesystem compared to another filesystem which is not dm-verity (both are on the same emmc block device). After executing I realized after that inspecting the backing_dev_info of each file coming from these 2 different locations point to the same 'block' backing_dev_info structure so this obviously wouldn't work out of the box as easily. Can one replace the backing_dev_info structure of a dm-verity block device with a custom one so I could add a 'trusted' flag to its capabilities? Then any file coming from that block device would allow me to verify the capabilities (in the kernel exec command for example). If that can't be done, is there any other avenue in the kernel where this sort of flag could be added and verified on a file? Hacking aorund in the kernel is all pretty new to me so I'm not aware of all the data structures invloved and how they relate to each other all over the kernel and its block/fs functionality. If you know of any level of documentation that explains how it works, that would also be great to help me digest all of this. Thanks David

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Fwd: Resend - ANNOUNCE: Netdev 0.1 conference
by Jeff Kirsher Nov. 20, 2014

Nov. 20, 2014

Please forward to all places you think are relevant. [original email i sent had the wrong contact info at the bottom should be: info(a)netdev01.info] Netdev 0.1 (year 0, conference 1) is a community-driven conference geared towards Linux netheads. Linux kernel networking and user space utilization of the interfaces to the Linux kernel networking subsystem are the focus. If you are using Linux as a boot system for proprietary networking, then this conference _may not be for you_. The netdev conference this year is structured to be 50/50 by-invitation and talk submission. We are making sure that we reach out to speakers who have interesting relevant topics because we recognize most of these folks would typically not be submitting papers to a conference. The invitation will be made by the technical committee to the individual speakers both for paper and tutorial sessions. The call for papers is for the 50% submission portion of the conference for both paper submission as well as tutorials. We *highly discourage* submission of recycled talks. Current topics include - wireless - performance analysis and improvement - networking hardware and offload - netfilter - traffic control - different networking layers (L2/3, etc) - internet of things - security - additional topics can be suggested We encourage submission of papers and tutorials. Unlike other conferences, we are going to try and accommodate as many submissions as possible - but please stay within the relevant topic focus and tie to Linux networking to make it easier for the technical committee to provide quick feedback. In order to give a talk you must be registered. If your proposal is accepted you will not be charged a conference fee or your conference fee will be refunded to you when your talk gets accepted. We will be posting more updates on how to submit in the near future. We expect about 3-4 parallel tracks both during tutorials and main talks. Tutorials will be on the first day and talks on subsequent days. Why you should register ----------------------- If you yearn for the old community tech driven conferences where you mingle with fellow geeks (only these would be Linux networking geeks) then this would be it. There will be no marketing flashy openings. There will just be a pure feed of Linux networking. netdev 0.1 will be held back to back with netconf 2015, the by-invite Linux kernel networking workshop (http://vger.kernel.org/netconf2015.html) So gurus of all sorts will be there mingling and giving talks. While there will be heavy Linux kernel influence we expect a lot of user space presence as well. Location: --------- Downtown Ottawa, Canada. Exact location to be announced. www.netdev01.org Important Dates: ---------------- November 26, 2014 Call for Papers opens December 10, 2014 Registration opens January 10, 2015 Call for sessions deadline January 20, 2015 Conference schedule announced February 14-17, 2015 Conference days Please register as soon as registration opens up on December 10. Registering helps us plan properly for numbers of attendees, ensuring venue sizes and supplies are appropriate without wasting resources. contact: -------- info(a)netdev01.info -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html -- Cheers, Jeff

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