January 2011 - kernelnewbies@kernelnewbies.org

most likely, i'll be giving a kernel talk at ottawa LUG next week
by Robert P. J. Day Jan. 27, 2011

Jan. 27, 2011

while i'm still waiting for official confirmation, i've offered to give next week's talk at the ottawa (ontario) linux users group. here's the current posting which doesn't mention it yet: http://oclug.on.ca/meeting/70/ since i'm in town and there was nothing on the schedule, i volunteered to give a short (hands-on) talk on building and booting a new kernel, and how to write, compile and load your first kernel module. nothing earth-shaking, but if you wanted to see that done step-by-step in real time and be able to ask questions as it's happening, stop by. i'm hoping that a synopsis goes up fairly soon. rday -- ======================================================================== Robert P. J. Day Waterloo, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================

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Added about new kernel on old distro (was Re: most likely, i'll be giving a kernel talk at ottawa LUG next week)
by Mulyadi Santosa Jan. 27, 2011

Jan. 27, 2011

On Thu, Jan 27, 2011 at 01:08, Robert P. J. Day <rpjday(a)crashcourse.ca> wrote: > since i'm in town and there was nothing on the schedule, i volunteered > to give a short (hands-on) talk on building and booting a new kernel, > and how to write, compile and load your first kernel module. nothing > earth-shaking, but if you wanted to see that done step-by-step in real > time and be able to ask questions as it's happening, stop by. If you don't mind, if someone ask you about how to run new kernel on such old distro, you could teach them about the thing I write here: http://the-hydra.blogspot.com/2011/01/making-latest-26x-linux-kernel-works.… -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com

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Cloning 'struct file'
by Daniel Baluta Jan. 27, 2011

Jan. 27, 2011

Hi all, We know that each file descriptor fd, has an associated 'struct file'. How is the 'struct file' copied/cloned at fork? Are all fields of 'struct file' inherited by child? I want to know if there is a function which takes a struct file* and creates a consistent copy/clone of it. thanks, Daniel.

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Multi core arch
by Sri Ram Vemulpali Jan. 27, 2011

Jan. 27, 2011

Hi, Can anyone point me to intel multicore datasheet of system programming guide or developers guide. I searched on Intel website, which I found programming guides for processor arch, but not for multicore archs. Please share if anyone has this information. -- Thanks, Sri.

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buffer page concepts in the page cache
by Miguel Telleria de Esteban Jan. 26, 2011

Jan. 26, 2011

Dear all, CONTEXT I am spending the last weeks learning how the kernel executes disk I/O writes and reads from the userland read() to the hard disk drive. I want to see (and understand) the WHOLE PICTURE regarding the VFS, block I/O layer and page cache. To do this, I am following as a base guide Bovet and Cesati UTLK 3rd edition [1] (chapters 12-16 so far) and the new edition of Robert Love's Linux Kernel Development[2] (chapters 13-16). A lot of reading so far that I still need to slowly digest. For the moment, I have not dived yet into the details of "page frame reclaiming", "swap memory" and "filesystem implementations" areas. My knowledge about memory allocation (slab allocator) is also limited. [1] Understanding The Linux Kernel 3rd Edition, O'Reilly [2] Linux Kernel Development 3rd Edition Addison Wesley MY QUESTIONS 1. What do we understand by "buffer pages"? 2. Is the whole page cache content (i.e. the radix tree in the address_space of the different inodes) organized as buffer pages? 3. What is the functional difference between "block device buffer pages" (stored in the address_space of the master bdev inode) and the "file buffer pages" stored in the address_space of a file inode? [ UTLK, page 614 ] Maybe I am missing an important point of course... MY INTERPRETATION (please correct me if I am wrong) Q1 What is a "buffer page"? A "buffer page" is a "struct page" data describing a page allocated to hold one or more i/o blocks from disk. As such, the "private" field points to a single circular list of "buffer_heads" each describing the mapping between the i/o blocks in memory (b_data field) and the i/o blocks on disk (b_size, b_blocknr...). The buffer_head structures themselves are stored outside of the page as shown in UTLK Fig 15.2. --- Q2 Is the whole page cache content organized as buffer pages? YES, there is no other way to link memory-mapped disk i/o data to the struct page pointed by address_space radix-tree entries. --- Q3 block device buffer_pages vs file buffer_pages This I really don't understand. From what UTLK page 614 says: * File buffer_pages ONLY refer to non-contiguous (on disk layout) file contents. * blockdev buffer_pages refer to single-block or continuous (on disk layout) portions of block. My question is: what happens with non-fragmented medium size files that do not contain "disk holes" or non-adjancent block submissions? Thanks in advance for your attention, Miguel

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Re: Asking advice for graduate study
by larry Jan. 26, 2011

Jan. 26, 2011

Understanding Linux Network Internals �� 2011��1��26�� 1:17��Alvin <qzhang.g(a)gmail.com>д�� > 2011/1/25 cheng chen <freakrobot(a)acm.org> > > > Hi, all! > > I am going to further my education in graduate school of Master of > Science > > degree. I am interested in network, but I am not sure what direction I > > should choose and which professional books I should read. Therefore I ask > > for help and suggestion from you. > > In summary, I have both the fundamental knowledge about network > programming > > as well as communication theory. Therefore I prefer an area which has the > > relationship with both the software and hardware (but with more attention > > one > > > HW and SW-->Embedded system, and keep going, don't stop > > > software.) By the way, I am especially interested in how the whole > network > > system works, rather than how two single points communicate. > > If you have any suggestion about what I could do next (areas, books, > > whaever~), > > please be kind to tell me. Thank you very much. > > > > -- > > Cheng(�\) > > > > Fedora Project Contributor -- Ambassador > > https://fedoraproject.org/wiki/User:Freakrobot > > _______________________________________________ > > > > My Page: http://freakrobot.blogbus.com/ > > _______________________________________________ > > Linux �ں˿��ʼ��б� > > Linux-kernel(a)zh-kernel.org > > http://zh-kernel.org/mailman/listinfo/linux-kernel > > Linux �ں˿�� http://zh-kernel.org > > > > > -- > > ~Alvin > _______________________________________________ > Linux �ں˿��ʼ��б� > Linux-kernel(a)zh-kernel.org > http://zh-kernel.org/mailman/listinfo/linux-kernel > Linux �ں˿�� http://zh-kernel.org >

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How to load and run a program (image) on to a fresh ARM based board?
by Madhavi Manchala Jan. 25, 2011

Jan. 25, 2011

Dear All, I am new to Board Support Package (BSP) development. I have few basic questions about BSP. The hardware devices that I have with me are as follows. 1) A custom board with Samsung S3C2510A micro controller which is based on ARM 940T core with some serial ports, ethernet ports and a JTAG interface. 2) J-Link JTAG with J-Flash and J-LinkGDBServer applications. My basic questions are, a) How can I load my program (image) on to the device flash? b) How can I copy my program from flash to RAM and run the same from RAM? c) Where can I see my program output? In brief, I want to load my application on to the device and run the same. How can I do this? What are other tools or applications I need? What other information I need like flash details, micro controller details etc.? Thanks and Regards, Madhavi M.

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possible regression?
by Mag Gam Jan. 25, 2011

Jan. 25, 2011

Running on Redhat 5.1 if I do, dd bs=1024 count=1000000 if=/dev/zero of=/dev/null I get around 30Gb/sec However, when I do this with 2.6.37 I get close to 5GB/sec Is there anything new in the kernel? TIA

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USB SUNRPC
by swathi suresh Jan. 25, 2011

Jan. 25, 2011

Hello, Am working on a project which is some thing like i receive the RPC message over USB, and redirect this message to SUNRPC server or network file server NFS(by manually decoding the RPC messages using XDR libs). So is this feasible or should i proceed with writing my own NFS in the user space. Background: I have written the USB device drivers and a network driver, which successfully return the data received via USB, to the user space program which has opened a socket to the address family and a protocol family i have implemented. I have gone though the source code of net/sunrpc and fs/nfsd

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Memory leak with dev_add_pack()
by Spiro Trikaliotis Jan. 25, 2011

Jan. 25, 2011

Hello, I have been tasked with writing a kernel module to handle an own protocol (with an own EtherType) in the Linux kernel. While I am not a complete newbie in the Linux kernel, having to handle Ethernet traffic there is new to me. I have looked at several tutorials and also at sample code (for example http://www.phrack.org/archives/55/p55_0x0c_Building%20Into%20The%20Linux%20…, and some tutorials I cannot find at the moment...) and tried to cut it down to the bare essentials. I came up with the following code utilising Linux Protocol Module: http://www.trikaliotis.net/testmodule/test_kernel.c the correspondig Makefile is in http://www.trikaliotis.net/testmodule/Makefile Note: This is a cut-down version of the actual code which shows the problem. Additionally, I register for ETH_P_ALL so the problem occurs as fast as possible. While it essentially works as I want it to, I found that I am leaking memory this way. Having this module in a highly loaded network, "head -n5 /proc/meminfo" shows that MemFree is steadily falling, until the kernel OOPS with an out of memory condition. "Of course", if I undefine DO_MEMLEAK, the memory leak does not occur anymore. I tried for almost two weeks now to look at different tutorials, and I also looked in working code (for example, the IP LPM) and tried to compare with my code, but I could not find out what I am doing wrong here. I am sure it must be something obvious, and very silly - unfortunaely, for me, it is not obvious at the moment. Can anyone help me here, please? Best regards, Spiro. -- Spiro R. Trikaliotis http://opencbm.sf.net/ http://www.trikaliotis.net/ http://www.viceteam.org/

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