June 2011 - kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

kernel list data structure
by Amirali Shambayati June 13, 2011

June 13, 2011

Hello all, I wanted to use list data structure implemented inside kernel. It seems that it is too different with usual concept from a list data structure. I studied about it, and I thought that I got familiar enough to use it. I have implemented a two-dimensioned list, using what I understood about kernel list. But as I debugged my code, it seems that my concept is wrong. Would anyone guide me how to implement a two-dimensioned list, or introduce me a manual to learn about it more? I have two data structures called "noop_data" and "bundle". I have a list of bundles, which each one has a list of requests. I implemented it, this way: "noop_data" has a reference to start point of bundles list, called "writeQueue" "bundle" has a reference to start point of requests list, called "reqsQueue". "bundle" knows its related list using "bundlesQueue". "request" knows its related list using "queuelist". (request struct is already implemented in kernel) struct bundle { int bundleNumber; int size; struct list_head bundlesQueue; struct list_head reqsQueue; int filled[8]; }; struct noop_data { struct list_head readQueue; struct list_head writeQueue; struct bundle bun; unsigned int starved; }; -- Amirali Shambayati Bachelor Student Computer Engineering Department Sharif University of Technology Tehran, Iran

3 9

How to write linux drivers?
by Lalit Pratap Singh June 13, 2011

June 13, 2011

Hi all, I am linux kernel newbie, I am trying to understand linux kernel since very long. Can anyone tell me how to understand drivers, How can i start working on writing drivers? I just wanted to know that, How can i write the smallest driver and test it? Also suggest me where to find the specification of the target hardware, for which driver is to be written? Ex. floppy drive, bluetooth etc. I want some basic tutorial links also. Thanks Lalit Pratap

4 3

interrupt
by Venkateswarlu P June 13, 2011

June 13, 2011

Is each key press is an interrupt ?

3 2

Problem with newly compiled kernel 2.6.39 (initrd.img not being created)
by Naman shekhar Mishra June 13, 2011

June 13, 2011

My platform is Intel 32 bit. I am using kernel 2.6.35-22 generic for these steps and the newly compiled kernel is 2.6.39 Here's my steps: $make defconfig $make -j2 CC="ccache gcc" $make modules #make modules_install #make install #update-grub After these sequence of steps, I tried to boot into the new kernel and there was nothing (except for the blinking caps lock) .So I checked and there was no initrd.img in /boot. So I tried using mkinitranfs and it created the ramdisk and then I booted but still it won't work. Though I can boot into recovery mode but the shell prompt is strange like (initramfs)...

3 2

system call
by Venkateswarlu P June 11, 2011

June 11, 2011

Where do i find system call implementation code? *for read, write, open, close*

3 2

Re: Calling function from address
by Micha M. June 11, 2011

June 11, 2011

On Fri, Jun 10, 2011 at 07:30:46AM +0800, Gavin Guo wrote: > > So maybe I have to explain some more. There is some code located in the > > pysical address space and I need to call it from a kernel module. The > > problem is, that the code must be run from that location it is stored (it > > contains absolute jumps). So I'd like to be able to run that code in that > > address space, or to "tell" the keeernel to ignore page faults/memory > > protection on a certain address range, so that I can jump there run the > > code and return to the caller (kernel module) > > What is the architecture do you use? ex: x86, arm, mips,... ARM. > I know in some platform like andes, it is possible to turn off the > virtual memory. > Then you can jump to the physical address. After doing what you want, turning on > virtual memory again. Finally, system return to the normal operation. > However, the > code is a little tricky. Before turning off the virtual memory, you > must lock the > code jumping to physical address in cache. Otherwise, behaviors, after > turning off > the cache, is unpredictable. > > Gavin Guo -- /* To err is human; to really fuck things up requires the root password */

2 2

writing pci device driver
by Daniel Redway June 11, 2011

June 11, 2011

Hi I have some question about writing device driver. I am reading some books and text. 1) I have device which have memory space 1 mb. and I mapped this memory using pci_iomap function. I read some text and they said if device need access mapped memory, you set the command register in configuration space. But which bit will ve set? only is enough only bit set PCI_COMMAND_MEMORY<http://lxr.linux.no/linux+*/+code=PCI_COMMAND_MEMORY> ? 2) I dont want to use dma first step. Maybe next time I will be use. PCI_COMMAND_MASTER <http://lxr.linux.no/linux+*/+code=PCI_COMMAND_MASTER> this command bit is only set when I use dma ? is it true? thanks.

1 0

System call question
by Naman shekhar Mishra June 11, 2011

June 11, 2011

Platform: x86 32 bit system_call() ,afetr doing some checks, looks up in the sys_call_table and finds the correct address of the system call and jumps to it. i.e.: call *sys_call_table(,%eax,4) Can you please explain this syntax to me. I think 'call' is the processor instruction which works on a function name. * is used in gas syntax to denote that the address following it is to be used as the jumping address. Tell me if I m wrong so far. () is used to index a memory location(GAS syntax again, I think). Please explain to me (,%eax,4). I have trouble understanding this syntax.

2 1

vmalloc alignment
by Mike Gibson June 10, 2011

June 10, 2011

In my limited testing, it seems that vmalloc gives memory that is page aligned. Is this always true? Mike Gibson

2 1

memory management
by Venkateswarlu P June 10, 2011

June 10, 2011

how to understand the memory management code in linux any suggestions

4 3