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question about alloc_bootmem
by javaweb zhang April 16, 2011

April 16, 2011

Hello, everyone. I use alloc_bootmem() in profile.c to allocate a big memory at function profile_init(), how I know whether it is success? The following is my code: // at kernel/profile.c ctxsw_A = (struct ctxsw_rec *)alloc_bootmem(sizeof(struct ctxsw_rec)*CTXSW); ctxsw_rec is a struct which declared in include/linux/profile.h, CTXSW = 4>>10

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Enabling Signals in kernel
by Vijay Ram Chitrapu April 16, 2011

April 16, 2011

Hi experts, I am using MVL6.0 in my project and have customized the kernel as per the requirement. However, i am facing a problem where the Ctrl+C signal doesn't get caught (or not sure if it is even generated) on the target platform. I have tried using the "trap" at the shell to capture the signal but the signal just doesn't get caught. Below is what i have done to try the trap way trap " " INT echo "Catching Ctrl+C signal" trap INT sleep 5 Putting this piece of code into a script doesn't catch the signal SIGINT (ctrl+c). To understand if it was a problem with the shell, i wrote a C code to register my own signal handler for SIGINT signal. To verify the correctness of the code, i executed the C code on the HOST server and it works well there (signal handler gets invoked when ctrl+c is pressed). Whereas, the same C code doesn't catch the Ctr+C signal in the target platform. Can someone tell me if there is any specific way to identify is there a way or rather is there a need to enable the signals explicitly while creating the config file for the kernel? Below is the output of "stty -a" command at the shell where i need to catch the Ctrl+C signal. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ / # stty -a speed 115200 baud; rows 24; columns 80; intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>; eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W; lnext = ^V; flush = ^O; min = 1; time = 0; -parenb -parodd cs8 hupcl -cstopb cread clocal crtscts -ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl ixon -ixoff -iuclc -ixany -imaxbel opost -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0 isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt echoctl echoke ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Regards, Vijay

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Problem with booting using qemu
by Minwoo Lee April 16, 2011

April 16, 2011

Hi, all. I want to study kernel, so I tried booting my custom compiled kernel on qemu with '-kernel' and '-initrd' option. First, I installed ubuntu 10.10 with cdrom, no LVM. $ qemu disk.img -cdrom ubuntu-10.10-server-i386.iso -vnc :1 After installation, I tried booting my custom compiled kernel(but not modified, just compiled). $ sudo qemu -m 512 -enable-kvm disk.img -nographic -append "console=ttyS0 root=/dev/sda1 ro" -kernel bzImage -initrd initrd.img-2.6.37 And I got result like this. [ 2.687558] EXT4-fs (sda1): INFO: recovery required on readonly filesystem [ 2.688085] EXT4-fs (sda1): write access will be enabled during recovery [ 2.691679] EXT4-fs (sda1): recovery complete [ 2.944387] EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts: (null) Begin: Running /scripts/local-bottom ... done. done. Begin: Running /scripts/init-bottom ... done. [ 2.988413] e1000 0000:00:03.0: eth0: (PCI:33MHz:32-bit) 52:54:00:12:34:56 [ 2.988871] e1000 0000:00:03.0: eth0: Intel(R) PRO/1000 Network Connection After that, the machine just stopped and I don't know the cause. What is the cause, or how to find the cause? The whole log is in this url. https://gist.github.com/916961 Thank you for reading.

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Netfilter and Tcpdump
by Sowmya Sridharan April 14, 2011

April 14, 2011

Hi, I was analyzing some tcpdump data, and noticed that it also captured packets mangled by Netfilter hooks. Theoretically I know that the pcap library takes off the packets from ethernet driver level and with the help of the dynamic filters set by userspace, we are able to see those packets via tcpdump. But aren't netfilter hooks attached at a higher level, namely the network stack? If so, then how is the pcap library able to sniff those packets as well? Is it like the pcap library just holds a reference to the packets it takes from the driver, or does it maintain a separate copy for displaying? Any answers/clarifications would be much appreciated. Thanks, Sowmya =====-----=====-----===== Notice: The information contained in this e-mail message and/or attachments to it may contain confidential or privileged information. If you are not the intended recipient, any dissemination, use, review, distribution, printing or copying of the information contained in this e-mail message and/or attachments to it are strictly prohibited. If you have received this communication in error, please notify us by reply e-mail or telephone and immediately and permanently delete the message and any attachments. Thank you

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Device Driver Help
by Naveen Kumar April 12, 2011

April 12, 2011

Hi, I am very new to device driver area and has some basic knowledge of char and block device driver and linux kernel. I am little bit aware of some of subsystem of kernel but I am not able to co-relate which device driver file is pure software driver and more or less part of kernel subsystem to achieve hardware abstraction and which driver files deals with real hardware. It would be great help if someone can provide some real example with some open hardware datasheet, some basic code snippet will help me a lot. Thanks, A Kernel Newbie

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BSP device driver customization
by Naveen Kumar April 11, 2011

April 11, 2011

Hi, I am new to BSP and HAL development. I have a IP which is using BSP released by some of leading ARM Soc maker. The IP is designed by our company where my job is to customize the device driver for my IP to achieve performance. Can anyone please suggest me a starting point to find the bug specific to my board(Hardware) and fix them. Thanks, Naveen

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order of call to built-in modules
by David Shwatrz April 11, 2011

April 11, 2011

HI, The macros module_init() and module_exit() are used both in case a source is built-in (the code is called from the init stage) or as a kernel module (implementing a init_module symbol). In case 2 of /built-in/ modules I am wondering if it is possible to know by advance the order used to call the various module_init() entry points. Is it possible to fix this order? rgs, DS

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Kernel newbie mailing list subscription
by Naveen Kumar April 11, 2011

April 11, 2011

please confirm my subscription. Thanks, Naveen

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inode query
by mohit verma April 8, 2011

April 8, 2011

hi list, how can a utility like **find** command can map an inode number to a filename? i mean if we pass **find -inum inode_number / ** , it will show us the files associated with that "inode_number". What is the underlying mechanism used in all this ? I have peeped into the findutils code but it seems horrible to figure it out from that code .:) thanks in advance. -- ........................ *MOHIT VERMA*

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Mentoring for GSoC
by Greg Freemyer April 7, 2011

April 7, 2011

All, I've seen a couple posts here from students looking for GSoC mentors. >From the flip side, I just had someone ask me if they could be a GSoC mentor via kernelnewbies. (I'm a proposed mentor via opensuse. Still looking for a student/proposal.) Does anyone know the details of the GSoC / kernelnewbies mentoring setup? Can someone just request to be a mentor via google-melange and say they are associated with kernel.org, and then say in the comments that they are part of kernelnewbies? ie. This org is so unstructured, I'm not sure how that would work. Thanks Greg

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