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

char driver error
by Aravind Vijayan May 9, 2011

May 9, 2011

Hi all, Let me begin this post with thanx all to whom help me on previous problem.I have completed jobs such as writing,making,inserting the module. i create a character special file using mknod in /dev directory. i try to write data to my file by" echo -n "abcd" > /dev/memory " and when i try to read from that file i get the last char was written to that file that is "d" here is my code:http://pastebin.com/9YsJetek

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Re: char driver error
by Manohar Vanga May 9, 2011

May 9, 2011

Google for "kmalloc": About 182,000 results (0.11 seconds) http://lwn.net/Kernel/LDD3/ http://tldp.org/LDP/lkmpg/2.6/html/index.html Make an effort. It usually helps :-) On Mon, May 9, 2011 at 1:57 PM, Aravind Vijayan <aravind1123(a)gmail.com>wrote: > On 5/9/11, Manohar Vanga <manohar.vanga(a)gmail.com> wrote: > > This line is incorrect. You need to learn how kmalloc (or any *alloc for > > that matter) works because it seems like you don't realise what is > happening > > with this statement. > > > > memory_buffer = kmalloc(1, GFP_KERNEL); > > > > > > I am totally newbie to kernel and to drivers i wish to study about > them seeking you all's help..... > -- /manohar

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RE: building a specific driver in kernel src tree
by sri May 9, 2011

May 9, 2011

Actually am using Centos-5.5 (kernel-2.6.18-194.el5) and trying to overwrite the e1000 drives with those in kernel-2.6.22. After resolving few symbols at compile time, when trying to load the kernel with this change, the e1000 probe method is failing with the error e1000: 0000:01:00.0: e1000_probe: The EEPROM Checksum Is Not Valid e1000: probe of 0000:01:00.0 failed with error -5 e1000: 0000:01:00.1: e1000_probe: The EEPROM Checksum Is Not Valid e1000: probe of 0000:01:00.1 failed with error -5 Am trying to debug that. Any help/pointers on why this occurs and how to resolve it? --Sri On Mon, May 9, 2011 at 11:35 AM, sri <bskmohan(a)gmail.com> wrote: > the config had it as CONFIG_E1000=y > Does =y or =m make any difference? > > still not working. > > > On Mon, May 9, 2011 at 11:32 AM, Jeff Kirsher <jeffrey.t.kirsher(a)intel.com > > wrote: > >> On Sun, May 8, 2011 at 22:49, sri <bskmohan(a)gmail.com> wrote: >> > Hi, >> > >> > As part of learning, I have added few debug statements to the code at >> > drivers/net/e1000/e1000_main.c (e1000_probe function). >> > Now to compile this, am doing make -C >> /lib/modules/2.6.18-194.el5PAE/build >> > M=`pwd` modules under drivers/net/e1000 dir. >> > >> > That is not compiling anything. But the same thing when I do in >> > drivers/net/e1000e, it is compiling and creating e1000e.ko file. >> > >> >> Check your kernel config file (which is .config) to make sure that >> CONFIG_E1000=m >> >> Then you should be able to run ` make drivers/net/e1000` to build the >> e1000 driver as a module >> >> > Any help on how to get e1000.ko? >> > >> > --Sri >> > _______________________________________________ >> > Kernelnewbies mailing list >> > Kernelnewbies(a)kernelnewbies.org >> > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >> > >> > >> >> >> >> -- >> Cheers, >> Jeff >> > > > > -- > -- > Krishna Mohan B > -- -- Krishna Mohan B -- -- Krishna Mohan B

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Understanding framebuffer drivers
by Ezequiel García May 9, 2011

May 9, 2011

Hi, I am trying to understand framebuffer drivers. I am looking through DirectFB code and have already coded some little examples that accesses my "radeondrmfb" device through ioctls() and mmap(). Also, I've found this link, but it is very outdated (kernel 2.2) http://www.linux-fbdev.org/HOWTO/index.html Is there any other resource I can read ? In particular, how can I know wich ioctl each driver implements without reading the code itself ? Greetings, Ezequiel.

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building a specific driver in kernel src tree
by sri May 9, 2011

May 9, 2011

Hi, As part of learning, I have added few debug statements to the code at drivers/net/e1000/e1000_main.c (e1000_probe function). Now to compile this, am doing make -C /lib/modules/2.6.18-194.el5PAE/build M=`pwd` modules under drivers/net/e1000 dir. That is not compiling anything. But the same thing when I do in drivers/net/e1000e, it is compiling and creating e1000e.ko file. Any help on how to get e1000.ko? --Sri

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Char driver
by Aravind Vijayan May 8, 2011

May 8, 2011

Hi all, i am totally newbie to drivers,but i like to deal with them . I have a code here:http://pastebin.com/9YsJetek when i try to make it, /*make file*/ obj-m +=memory.o all: make -C /lib/modules/$(shell uname -r)/build M=$(pwd) modules clean: make -C /lib/modules/$(shell uname -r)/build M=$(pwd) clean /*End*/ i got some error: make -C /lib/modules/2.6.35.12-90.fc14.i686/build M= modules make[1]: Entering directory `/usr/src/kernels/2.6.35.12-90.fc14.i686' CHK include/linux/version.h CHK include/generated/utsrelease.h make[2]: *** No rule to make target `missing-syscalls'. Stop. make[1]: *** [prepare0] Error 2 make[1]: Leaving directory `/usr/src/kernels/2.6.35.12-90.fc14.i686' make: *** [all] Error 2 how can i fix this.... Thanks in advance.

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so what's the deal with the proposed /sys/subsystem?
by Robert P. J. Day May 7, 2011

May 7, 2011

still methodically perusing the courseware i'll be teaching week after next, right now going through section on kobjects and sysfs and reading the kernel doc file Documentation/sysfs-rules.txt, which mentions a proposed /sys/subsystem hierarchy which, when(?) it exists, will obsolete /sys/{bus,class,block}. so what's the current status of this subsystem directory? is there a timeline for this? just curious. 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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anyone using "sysfsutils" in a practical way?
by Robert P. J. Day May 6, 2011

May 6, 2011

as i'm reviewing the courseware i'll be teaching in a couple weeks, i'm making notes as to what should go, what should stay and what should be added to bring it entirely up to date. i'm going to de-emphasize proc files, other than to show some examples in the fs/proc/ directory if students want to hack up a couple simple ones for their drivers, knowing that they're not meant to be permanent. and i want to more emphasize kobjects and sysfs. to that end, i'm aware of the "sysfsutils" package, although i haven't used it yet. is anyone familiar with it, to the point they're *using* it for useful things, as opposed to just playing with it? i'll probably get around to checking it out this weekend, just curious as to how i'd promote its use if/when the time comes. thanks. 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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Network packet processing related Query
by Sachin Rane May 6, 2011

May 6, 2011

Hi, I want to improve my understanding about the logic of the code written for 'process_backlog ()' . File Source: net/core/dev.c, linux-2.6.16 I am considering only Non-NAPI network devices ( > 1) in this discussion. The 'net_rx_action' function invokes 'dev->poll(dev, &budget)' for each network device present in 'poll_list'. ' The default handler for Non-NAPI network devices is 'process_backlog ()'. The signature of the function is: static int process_backlog (struct net_device *backlog_dev, int *budget) 'backlog_dev' represents the device for which the 'poll' function is invoked. In the code body the function acts on CPU specific 'input_pkt_queue'. This queue holds all the incoming packets from the network devices and 'poll_list' has reference for these network devices. The function takes out one element (packet) from the 'input_pkt_queue' and process the packet. As the 'input_pkt_queue' is shared by all the network devices, the 'packet' which is popped-out from the list can be from any network device not required to be from 'backlog_dev' (the device for which 'process_backlog' has been called). I have confusion here. The code doesn't operate only on the packets queued-in by 'backlog_dev' to 'input_pkt_queue'. It pops-out the node from the queue and process it. But it updates the 'quota' which is specific for the device 'backlog_dev' for which the function have got called. Why it is so? Am I missing out something here? Thanks for reading my mail patiently. Regards, Sachin Rane

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Serial Port Monitoring Tool
by Madhavi Manchala May 6, 2011

May 6, 2011

Dear All, We have gone through following link about the serial monitoring tool. http://tldp.org/HOWTO/Serial-HOWTO-11.html#serial_mon However, we know about the USBMON which is used to monitor the USB traffic on the USB bus. Like USBMON, which is the best one? Is there any other tool, apart from the above link, for monitoring the serial data?\ Thanks in advance. Regards, Madhavi M.

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