October 2012 - kernelnewbies@kernelnewbies.org

How to get the inode - no path_lookup
by Rishi Agrawal Sept. 17, 2015

Sept. 17, 2015

Hi All, I had a module which used the path_lookup function to print the details of any file's inode. I now want to rewrite that module in order to show some juniors how to write some code in kernel. I am using 3.4.6 kernel, I tried finding out path_lookup but google showed that it has been removed. I tried the following code then which did not work . . . dentry = kern_path_create(AT_FDCWD, filename, &path, 1); if (IS_ERR(dentry)) { printk("Failed to obtain the dentry"); return; } its not returning dentry I again tried after seeing the implementation of vfs_stat function user_path_at(AT_FDCWD, filename, lookup_flags, &path); but this also fails. I am using a proc interface to pass the filename, and copying the filename into a kernel buffer. How can I get a copy of vfs inode for a file name. -- Regards, Rishi Agrawal

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linux segment
by Fan Yang June 20, 2013

June 20, 2013

Hi all: I print the cs ds and ss register in the user space, and it is same as the __USER_CS and __USER_DS which defined in kernel as 73 and 7b. In the kernel __KERNEL_CS and __KERNEL_DS defined as 60 and 68, but when I print this two value in my kernel module, I get 60 and 7b. Why ? It should be 60 and 68, shouldn't it?

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Debug symbols in kernel modules
by Aft nix Dec. 2, 2012

Dec. 2, 2012

Hi, When i write a makefile to build a kernel module how should i make sure that it contains debugging symbols? So that when i will use gdb over serial line to debug the module, i can use "add-symbol-file"? -- -aft

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Tools for checking incorrect usage of locking techniques in k-space
by Kumar amit mehta Nov. 6, 2012

Nov. 6, 2012

Hi, I recently came across this tool called KEDR[1] for checking memory leak in kernel modules. I'm using it to check If my trivial kernel modules (based on LDD3 examples) are leaking memory. I was wondering if there exist a similar tool for checking incorrect usage of locking techniques implemented by kernel module. -Amit [1]: http://kedr.berlios.de/

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If I don't active the page mechanism
by Fan Yang Nov. 3, 2012

Nov. 3, 2012

Hi all: I have a problem, if i don't active the page mechanism just use the segment mechanism at the x86 cpu, how can I manage the Multi-tasking? My view is to use the different base and limit in segment mechanism to divides different task, but this way will cause another problem that is the task which will run must have know which way another tasks line in the memery, if not ,this task may have Conflict with other tasks. If it is true, who can tell the infomation to the task? and if not, how to manage the Muit-tasking just use the segment mechanism? thanks Fan

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memory management with mmap
by Sengottuvelan S Nov. 1, 2012

Nov. 1, 2012

Hi All I am trying to experiment a memory management - allocate memory segments in Kernel space (junk of memory segments using page allocation) so that different user process can use/access it(read/write) using mmap. For example, I have 2 different user space process A,B etc. I have to allocate memory in Kernel for each of those processes (for example 2 pages) . Each process is allowed to use only 1 page using mmap from user space. Is it possible to do with mmap?. -- Regards, S. Sengottuvelan.

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RE: IPV6 related constants for netlink socket
by Murali Annamneni Oct. 31, 2012

Oct. 31, 2012

Hi, I'm trying to create a Netlink socket to configure an ipv6 interface. The socket call I used is - socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE6); I'm getting compiler error "error: NETLINK_ROUTE6 undeclared (first use in this function)" And I'm facing the same problem for "AF_NETLINK6". I grep'ed in source code of 2.6.32 kernel and system header files, I didn't find anywhere these constants. Are these constants are correct ? If not, what are the correct one's and in which header file I can find them. Thanks & Regards Murali Annamneni ::DISCLAIMER:: ---------------------------------------------------------------------------------------------------------------------------------------------------- The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. E-mail transmission is not guaranteed to be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or may contain viruses in transmission. The e mail and its contents (with or without referred errors) shall therefore not attach any liability on the originator or HCL or its affiliates. Views or opinions, if any, presented in this email are solely those of the author and may not necessarily reflect the views or opinions of HCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of authorized representative of HCL is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. Before opening any email and/or attachments, please check them for viruses and other defects. ----------------------------------------------------------------------------------------------------------------------------------------------------

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IPV6 related constants for netlink socket
by Murali Annamneni Oct. 30, 2012

Oct. 30, 2012

Hi, I'm trying to create a Netlink socket to configure an ipv6 interface. The socket call I used is - socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE6); I'm getting compiler error "error: NETLINK_ROUTE6 undeclared (first use in this function)" And I'm facing the same problem for "AF_NETLINK6". I grep'ed in source code of 2.6.32 kernel and system header files, I didn't find anywhere these constants. Are these constants are correct ? If not, what are the correct one's and in which header file I can find them. Thanks & Regards Murali Annamneni ::DISCLAIMER:: ---------------------------------------------------------------------------------------------------------------------------------------------------- The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. E-mail transmission is not guaranteed to be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or may contain viruses in transmission. The e mail and its contents (with or without referred errors) shall therefore not attach any liability on the originator or HCL or its affiliates. Views or opinions, if any, presented in this email are solely those of the author and may not necessarily reflect the views or opinions of HCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of authorized representative of HCL is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. Before opening any email and/or attachments, please check them for viruses and other defects. ----------------------------------------------------------------------------------------------------------------------------------------------------

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Etiquette of submitting patches for fixing coding style.
by Eugene Voronkov Oct. 29, 2012

Oct. 29, 2012

I watched Kroah-Hartman's video[1] on submitting patches where he walks through the process of fixing coding style. I feel like this would be a good way for me to jump into the process but I need more information. At what point do code style patches stop being more trouble then they're worth to the maintainers? For example, running checkpatch.pl against all files is showing around 3 non-trivial style violations per file. Would a patch fixing 12 violations across 4 files be worth submitting? 1. http://www.youtube.com/watch?v=LLBrBBImJt4

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a quick wiki page on kernel-doc
by Robert P. J. Day Oct. 27, 2012

Oct. 27, 2012

http://www.crashcourse.ca/wiki/index.php/Kernel-doc this also represents potential for cleanup since, when you run something like $ make htmldocs you'll get warnings when the inline documentation doesn't match the corresponding function/structure/enum, etc. so let's of room for documentation cleanup. rday -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================

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