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text segment corruption - probable suspects?
by Boyan Vladinov Jan. 24, 2014

Jan. 24, 2014

Hey guys, recently I experience .text segment corruption in Kernel space. Could someone give some hints which can be the reason for this text segment corruption, because as we know it is read-only? Thanks, nayobix --

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Linux Routing algorithm
by Binoy Jayan Jan. 24, 2014

Jan. 24, 2014

Hi all, I am working on an IP packet routing algorithm and intend to implement and test it using a linux box used as a router. Could anyone of you help me in adding my own algorithm for the same. ? Is it possible to register an routing algorithm similar to how a scheduling policy is registered. Please keep the email "binoyjayan(a)gmail.com" in CC as I am not a subscriber to this list. Thanks in advance, *Binoy Jayan*

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IP packet routing algorithm
by Binoy Jayan Jan. 24, 2014

Jan. 24, 2014

Hi all, I am working on an IP packet routing algorithm and intend to implement and test it using a linux box used as a router. Could anyone of you help me in adding my own algorithm for the same. ? Is it possible to register an routing algorithm similar to how a scheduling policy is registered. Please keep the email "binoyjayan(a)gmail.com" in CC as I am not a subscriber to this list. Thanks in advance, *Binoy Jayan*

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Example on signing a LKM?
by Ursa Major Jan. 24, 2014

Jan. 24, 2014

Hi Greg (or anyone who can advise), I have been browsing on: https://kernel.googlesource.com/pub/scm/linux/kernel/git/dhowells/linux-mod… I heard that the CONFIG_MODULE_SIG has to be turned on, but it was not stated particularly how. I am also not sure how to use a kernel make command. I also found this http://unix.stackexchange.com/questions/74022/sign-a-module-after-kernel-co… but cannot piece together enough to run a mini signed LKM. Would you guide me on a minimallist example on signing a helloworld LKM? Thank you, Greg. Sincerely, Michael

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callback function of ctl_table
by Guibin(Bill) Tian Jan. 21, 2014

Jan. 21, 2014

Hi, I am adding my own sysctl variable. And also I need a callback function whenever I modify this sysctl variable. There was once a ctl_handler member for the struct of ctl_table but now it has been removed. Is there any other way I can implement my callback method? Thanks Bill

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mmap CMA area on /dev/mem
by Кирилл Луценко Jan. 21, 2014

Jan. 21, 2014

Hello everyone! I need reserve 256-512 Mb of continuous physical memory and have access to this memory from the user space. I decided to use CMA for memory reserving. Here are the steps on my idea that must be performed: 1. Reservation required amount of memory by CMA during system booting. 2. Parsing of CMA patch output which looks like for example: "CMA: reserved 256 MiB at 27400000" and saving two parameters: size of CMA area = 256*1024*1024 bytes and phys address of CMA area = 0x27400000. 3. Mapping of CMA area at /dev/mem file with offset = 0x27400000 using mmap(). (Of course, CONFIG_STRICT_DEVMEM is disabled) It would let me to read data directly from phys memory from user space. But the next code make segmentation fault(there size = 1Mb): int file; void* start; file=open("/dev/mem", O_RDWR | O_SYNC); if ( (start = mmap(0, 1024*1024, PROT_READ | PROT_WRITE, MAP_SHARED, file, 0x27400000)) == MAP_FAILED ){ perror("mmap"); } for (int offs = 0; offs<50; offs++){ cout<<((char *)start)[offs]; } Output of this code: "mmap: Invalid argument". When I changed offset = 0x27400000 on 0, this code worked fine and program displayed trash. It also work for alot of offsets which I looked at /proc/iomem. According to information from /proc/iomem, phys addr of CMA area (0x27400000 on my system) always situated in System RAM. Does anyone have any ideas, how to mmap CMA area on /dev/mem? What am I doing wrong? Thanks alot for any help!

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How update happen for pt_regs
by naveen yadav Jan. 21, 2014

Jan. 21, 2014

Dear All, I want to dump ARM registers, show_regs(regs) in spin_dump() function. But show_regs get called only from traps or fault code. Any idea how we can do in normal scenario ? Also I check code pt_regs got updated in entry-armv.S, If any body have more idea how it is done. Thanks

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Dirtying inodes from block driver
by Rick Ramstetter Jan. 20, 2014

Jan. 20, 2014

I've got a block storage driver whose backing device can dirty data on-disk without OS action. How can I communicate that dirtied state to vfs such that caches are purged, etc? Data dirtied by the backing device is only known asynchronously. I think I need to solve this in request_fn(). Thanks

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Re: tcp packet split
by Augusto Mecking Caringi Jan. 19, 2014

Jan. 19, 2014

On Sun, Jan 19, 2014 at 2:31 AM, <net.study.sea(a)gmail.com> wrote: > How does the application level recognize each segment bridge in tcp stream > ? > i.e packe a 30bytes>> packet b 50bytes >>packet a 20bytes > And why it is possible for one packet to contain uncontinuous part of > different user protocol packets? > Take a look here also: http://www.wireshark.org/docs/wsdg_html_chunked/ChDissectReassemble.html -- Augusto Mecking Caringi

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How to access a DRM CRTC's scan out buffer?
by Sannu K Jan. 19, 2014

Jan. 19, 2014

Hi, I would like to access a monitor's content in kernel mode. I tried but could not find a generic way to access CRTC's scan out buffer in kernel mode. I prefer to do it in kernel mode as an experiment. Any pointers will greatly help. Thanks and Regards, Sannu K

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