January 2011 - kernelnewbies@kernelnewbies.org

Regarding Linux device driver Project
by ashutosh mishra Jan. 23, 2011

Jan. 23, 2011

> hi > i want to write a driver for DIO-48S PCI Card > (its automation Project - Aluminium Foil Winding Automated System Using PCI Interface) >i want to ask that what are the..prerequesite...for the Project... > i hav konwledge of C,89c51 Microcontroller,Arm Processor......... > but i am not able to start...........i hav gonr through Kernelnewbies(a)kernelnewbies.org Collected lots of information. > so please ...any one can help...???????? >its Urgent Require..... Thanks anr Regard , Ashutosh > From: kernelnewbies-request(a)kernelnewbies.org > Subject: Kernelnewbies Digest, Vol 2, Issue 50 > To: kernelnewbies(a)kernelnewbies.org > Date: Thu, 20 Jan 2011 12:00:01 -0500 > > Send Kernelnewbies mailing list submissions to > kernelnewbies(a)kernelnewbies.org > > To subscribe or unsubscribe via the World Wide Web, visit > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > or, via email, send a message with subject or body 'help' to > kernelnewbies-request(a)kernelnewbies.org > > You can reach the person managing the list at > kernelnewbies-owner(a)kernelnewbies.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Kernelnewbies digest..." > > > Today's Topics: > > 1. Re: Running kmemleak without sysfs support (Daniel Baluta) > 2. Re: possible regression? (Mag Gam) > 3. Re: possible regression? (Greg Freemyer) > 4. Re: Regarding Kernel Project (Greg KH) > 5. Re: Running kmemleak without sysfs support (Greg KH) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Thu, 20 Jan 2011 14:33:36 +0200 > From: Daniel Baluta <daniel.baluta(a)gmail.com> > Subject: Re: Running kmemleak without sysfs support > To: Catalin Marinas <catalin.marinas(a)arm.com> > Cc: kernelnewbies(a)kernelnewbies.org > Message-ID: > <AANLkTi%3DmEiha0rBOrX05xR%3DRy5-otsB9faC29RZK7K4a(a)mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > On Thu, Jan 20, 2011 at 12:52 PM, Catalin Marinas > <catalin.marinas(a)arm.com> wrote: > > On Thu, 2011-01-20 at 10:41 +0000, Daniel Baluta wrote: > >> Can I make any use of kmemcheck if I don't have sysfs > >> kernel support enabled? > > > > Kmemleak can scan output the memory and report the number of leaked > > objects but if you need to get additional information about the leaked > > objects (like backtrace), you need debugfs enabled. > > How is this reporting done? It will appear in dmesg output? > > > DEBUG_FS doesn't seem to be dependent on SYSFS but I never tried to > > enable one without the other (you might be able to mount the DEBUG_FS > > somewhere other than /sys/kernel/debug/). > > I see. I was using 2.6.32 where it seems that debugfs depended on sysfs. > Decoupling was done some time later [1]. > > thanks, > Daniel. > > [1] http://kerneltrap.org/mailarchive/linux-kernel/2010/8/5/4603446 > > > > ------------------------------ > > Message: 2 > Date: Thu, 20 Jan 2011 07:50:38 -0500 > From: Mag Gam <magawake(a)gmail.com> > Subject: Re: possible regression? > To: Mulyadi Santosa <mulyadi.santosa(a)gmail.com> > Cc: Kernelnewbies(a)kernelnewbies.org > Message-ID: > <AANLkTiks-aBqGcYFBUyZ%3DLDGJsTNFOhTdie60O8aCS7i(a)mail.gmail.com> > Content-Type: text/plain; charset=UTF-8 > > I am using RHEL 5.1. Sorry for not being clear. > > I wil give this a try today when I go back to class. But I was just > curious why this was happening. How would one disable "block merge" > efficiency? Has this feature been added recently? > > On Thu, Jan 20, 2011 at 12:28 AM, Mulyadi Santosa > <mulyadi.santosa(a)gmail.com> wrote: > > Hi... > > > > On Thu, Jan 20, 2011 at 10:36, Mag Gam <magawake(a)gmail.com> wrote: > >> Running on Redhat 5.1 if I do, > > > > Are you sure you're using that archaic distro? Or are you talking > > about RHEL 5.1? > > > >> dd bs=1024 count=1000000 if=/dev/zero of=/dev/null > >> > >> I get around 30Gb/sec > > > > Hm, mine is: > > $ dd bs=1024 count=1000000 if=/dev/zero of=/dev/null > > 1000000+0 records in > > 1000000+0 records out > > 1024000000 bytes (1.0 GB) copied, 1.12169 seconds, 913 MB/s > > > > This is on 2.6.36 SMP kernel compiled with gcc version 4.1.2 20080704 > > (Red Hat 4.1.2-48). > > > >> > >> However, when I do this with 2.6.37 I get close to 5GB/sec > > > > what if you use another blocksize, let's say 4K or even 32K? here's > > mine (again): > > $ dd bs=4K count=1000000 if=/dev/zero of=/dev/null > > 1000000+0 records in > > 1000000+0 records out > > 4096000000 bytes (4.1 GB) copied, 1.31167 seconds, 3.1 GB/s > > > > $ dd bs=32K count=1000000 if=/dev/zero of=/dev/null > > 1000000+0 records in > > 1000000+0 records out > > 32768000000 bytes (33 GB) copied, 4.91775 seconds, 6.7 GB/s > > > > see the difference? > > > > IMHO it's a matter of what I call "block merge efficiency"....the more > > you stuff pages (that fits into a "magic" number), the faster I/O you > > got. > > > > -- > > regards, > > > > Mulyadi Santosa > > Freelance Linux trainer and consultant > > > > blog: the-hydra.blogspot.com > > training: mulyaditraining.blogspot.com > > > > > > ------------------------------ > > Message: 3 > Date: Thu, 20 Jan 2011 09:29:20 -0500 > From: Greg Freemyer <greg.freemyer(a)gmail.com> > Subject: Re: possible regression? > To: Mulyadi Santosa <mulyadi.santosa(a)gmail.com> > Cc: Kernelnewbies(a)kernelnewbies.org, Mag Gam <magawake(a)gmail.com> > Message-ID: > <AANLkTinkqXqYU8MVYma%3D5Zo2_gTZ61ZGKn%2Bx%2B_zT6AeM(a)mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > Mulyadi, > > You disappoint me. ;( > > Just kidding, but discussing dd throughput without the > "conv=fdatasync" parameter is just a waste of everyone's time. > > And Mag, use a big enough count that it at least takes a few seconds > to complete. A tenth of a second or less is just way to short to use > as a benchmark. > > Greg > > On Thu, Jan 20, 2011 at 12:28 AM, Mulyadi Santosa > <mulyadi.santosa(a)gmail.com> wrote: > > Hi... > > > > On Thu, Jan 20, 2011 at 10:36, Mag Gam <magawake(a)gmail.com> wrote: > >> Running on Redhat 5.1 if I do, > > > > Are you sure you're using that archaic distro? Or are you talking > > about RHEL 5.1? > > > >> dd bs=1024 count=1000000 if=/dev/zero of=/dev/null > >> > >> I get around 30Gb/sec > > > > Hm, mine is: > > $ dd bs=1024 count=1000000 if=/dev/zero of=/dev/null > > 1000000+0 records in > > 1000000+0 records out > > 1024000000 bytes (1.0 GB) copied, 1.12169 seconds, 913 MB/s > > > > This is on 2.6.36 SMP kernel compiled with gcc version 4.1.2 20080704 > > (Red Hat 4.1.2-48). > > > >> > >> However, when I do this with 2.6.37 I get close to 5GB/sec > > > > what if you use another blocksize, let's say 4K or even 32K? here's > > mine (again): > > $ dd bs=4K count=1000000 if=/dev/zero of=/dev/null > > 1000000+0 records in > > 1000000+0 records out > > 4096000000 bytes (4.1 GB) copied, 1.31167 seconds, 3.1 GB/s > > > > $ dd bs=32K count=1000000 if=/dev/zero of=/dev/null > > 1000000+0 records in > > 1000000+0 records out > > 32768000000 bytes (33 GB) copied, 4.91775 seconds, 6.7 GB/s > > > > see the difference? > > > > IMHO it's a matter of what I call "block merge efficiency"....the more > > you stuff pages (that fits into a "magic" number), the faster I/O you > > got. > > > > -- > > regards, > > > > Mulyadi Santosa > > Freelance Linux trainer and consultant > > > > blog: the-hydra.blogspot.com > > training: mulyaditraining.blogspot.com > > > > _______________________________________________ > > Kernelnewbies mailing list > > Kernelnewbies(a)kernelnewbies.org > > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > > > > -- > Greg Freemyer > Head of EDD Tape Extraction and Processing team > Litigation Triage Solutions Specialist > http://www.linkedin.com/in/gregfreemyer > CNN/TruTV Aired Forensic Imaging Demo - > ?? http://insession.blogs.cnn.com/2010/03/23/how-computer-evidence-gets-retrie… > > The Norcross Group > The Intersection of Evidence & Technology > http://www.norcrossgroup.com > > > > ------------------------------ > > Message: 4 > Date: Thu, 20 Jan 2011 07:12:27 -0800 > From: Greg KH <greg(a)kroah.com> > Subject: Re: Regarding Kernel Project > To: Mulyadi Santosa <mulyadi.santosa(a)gmail.com> > Cc: kernelnewbies <Kernelnewbies(a)kernelnewbies.org> > Message-ID: <20110120151227.GA12768(a)kroah.com> > Content-Type: text/plain; charset=us-ascii > > On Thu, Jan 20, 2011 at 12:32:39PM +0700, Mulyadi Santosa wrote: > > On Thu, Jan 20, 2011 at 10:01, Greg KH <greg(a)kroah.com> wrote: > > > On Wed, Jan 19, 2011 at 09:11:53PM -0500, Pein Junior wrote: > > >> > > >> > > >> > What is the USB device and vendor id? > > >> > > >> Hope this manual help explaining all that. > > > > Guys, I don't wanna ruin your discussion, but don't you think it's OOT > > now? or are we going to rename this list as chitchat@vger.org? > > This is how you both solve bugs, and learn about solving them yourself. > > I'll be glad to take this to the linux-usb or linux-kernel lists, as > this type of conversation is quite common there, so why wouldn't it also > be common here? > > If it's annoying you, I suggest getting a better email client, one that > lets you mark any thread as "ignored" so we don't bother you. > > best of luck, > > greg k-h > > > > ------------------------------ > > Message: 5 > Date: Thu, 20 Jan 2011 07:56:57 -0800 > From: Greg KH <greg(a)kroah.com> > Subject: Re: Running kmemleak without sysfs support > To: Daniel Baluta <daniel.baluta(a)gmail.com> > Cc: catalin.marinas(a)arm.com, kernelnewbies(a)kernelnewbies.org > Message-ID: <20110120155657.GA29375(a)kroah.com> > Content-Type: text/plain; charset=us-ascii > > On Thu, Jan 20, 2011 at 12:41:57PM +0200, Daniel Baluta wrote: > > Hello all, > > > > Can I make any use of kmemcheck if I don't have sysfs > > kernel support enabled? > > Why would you ever want to run a kernel without sysfs support? If you > turn it off, you loose a _lot_ of functionality that you will need to > add back to your system in some other manner. > > What, specifically, is wrong with sysfs that is solved by turning it > off? > > thanks, > > greg k-h > > > > ------------------------------ > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies(a)kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > End of Kernelnewbies Digest, Vol 2, Issue 50 > ********************************************

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Ramdisk not working on Hawkboard
by Giriprasad Deviprasad Jan. 23, 2011

Jan. 23, 2011

Hi, I am creating ram disk as in : http://processors.wiki.ti.com/index.php/Creating_a_Root_File_System_for_Lin… I compiled the linux-omap kernel using (http://hawkboard.googlecode.com/files/linux-omapl1_ver1.tar.bz2) with the kernel parameters as described in the first link as above: make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- uImage_v2 cp arch/arm/boot/Image_v2 /tftpboot/uImage_v2 Then I did: setenv bootargs mem=88M ip=dhcp console=ttyS0,115200n8 root=/dev/ram0 rw initrd=0xc1180000,16M ramdisk_size=16384 saveenv tftp c0000000 uImage_v2 tftp c1180000 rd-ext2.bin bootm c0000000 It errors: hawkboard.org > bootm c0000000 AIS U-BootLoader is already flashed Wrong Image Format for bootm command ERROR: can't get kernel image! any clues why? This from http://elinux.org/Hawkboard works fine, though, with the default ram disk on hawkboard.org: http://hawkboard.googlecode.com/files/linux-omapl1_ver1.tar.bz2 make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- distclean make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- omapl138_hawkboard_defconfig make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- uImage Regards, D.Giriprasad

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Re: Memory leak with dev_add_pack()
by Spiro Trikaliotis Jan. 23, 2011

Jan. 23, 2011

Hello Anish, * On Sat, Jan 22, 2011 at 11:02:12PM +0530 anish kumar wrote: >> I have been tasked with writing a kernel module to handle an own >> protocol (with an own EtherType) in the Linux kernel. > > are you writing a kernel based sniffer?? Not really. I should take a custom protocol (with its own EtherType) and tunnel it in a specific way to another machine. In this sense: Yes, it is a sniffer. However, as I wrote in my original mail, I used ETH_P_ALL instead of the EtherType I need in order to make sure that I am leaking more memory, so people can see it themselves faster. >> http://www.trikaliotis.net/testmodule/test_kernel.c > > which kernel version are you using and above code would not be sufficient > to find out the problem.Can > you send the above file and makefile as well?? The problem occurrs with different kernel versions, as I wrote in my other mail. It is a 2.6.26-2-686 from Debian Lenny, and a kernel on Ubuntu 10.04, also 32 bit. Unfortunately this machine is currently out of my reach, but I think it is a variant of 2.6.32 or 2.6.33. The Makefile is already there, see the next part of my original message: >> the correspondig Makefile is in >> http://www.trikaliotis.net/testmodule/Makefile >> While it essentially works as I want it to, I found that I am leaking > > if it is sniffer are you getting all the packets??? I would say yes. The fully functional version works as expected, if I neglect the memory leak. Thus, I would expect I get all of the packets I need. Best regards, Spiro. -- Spiro R. Trikaliotis http://opencbm.sf.net/ http://www.trikaliotis.net/ http://www.viceteam.org/

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dd test discussion (was Re: possible regression?)
by Mulyadi Santosa Jan. 23, 2011

Jan. 23, 2011

On Fri, Jan 21, 2011 at 20:25, Mag Gam <magawake(a)gmail.com> wrote: > Typo, in Box 5. Wrong kernel version > > Box 5, RHEL 5.4, 2.6.36, dd bs=1024 count=1000000 if=/dev/zero > bs=4096k of=/dev/null > > Anyone had a chance to try this? :-) $ for a in `seq 1 3`; do \time dd bs=4K count=1M if=/dev/zero of=/dev/null; done 1048576+0 records in 1048576+0 records out 4294967296 bytes (4.3 GB) copied, 1.38893 seconds, 3.1 GB/s 0.21user 1.17system 0:01.39elapsed 99%CPU (0avgtext+0avgdata 2768maxresident)k 0inputs+0outputs (0major+209minor)pagefaults 0swaps 1048576+0 records in 1048576+0 records out 4294967296 bytes (4.3 GB) copied, 1.39358 seconds, 3.1 GB/s 0.23user 1.16system 0:01.39elapsed 99%CPU (0avgtext+0avgdata 2768maxresident)k 0inputs+0outputs (0major+209minor)pagefaults 0swaps 1048576+0 records in 1048576+0 records out 4294967296 bytes (4.3 GB) copied, 1.4527 seconds, 3.0 GB/s 0.17user 1.23system 0:01.45elapsed 96%CPU (0avgtext+0avgdata 2752maxresident)k 0inputs+0outputs (0major+208minor)pagefaults 0swaps I slightly modified your dd test. Again, this is on 2.6.36. IMO, you shouldn't worry much about it. Were experiencing something that related to memory access? It's not a NUMA box, right? Or are you using PAE? just capping into 896 MB maybe? non standart VM split other than 3:1? PS: I rewrite the subject to better match the discussion. With the hope readers well get better understanding about what the discussion is all about. Hope you don't mind.... -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com

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Learning to program at the operating system level
by vorad Jan. 22, 2011

Jan. 22, 2011

I was recently reading some old LWN article[1] about a realtime workshop in which was stated that the academia doesn't prepare CS graduates for working with the development community and more over, they don't know to program at the operating system level. What does programming at the operating system level mean and what does it involve ? How's that different than what's currently happening in software development, what are the constraints and what should an engineer expect when it enters the realm of OSs ? Thanks! [1] http://lwn.net/Articles/355416/

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what does mean softfp. gcc related
by lei yang Jan. 21, 2011

Jan. 21, 2011

Hi list, I confused by arm gcc flags In gcc user guide: -mfloat-abi=name `softfp' allows the generation of code using hardware floating-point instructions, but still uses the soft-float calling conventions. `hard' allows generation of floating-point instructions and uses FPU-specific calling conventions. eg: -mfpu=vfp -mfloat-abi=softfp what does this mean if arm support vfp instructions. what's the different between "-mfpu=vfp -mfloat-abi=softfp" and "-mfpu=vfp -mfloat-abi=hard". can someone give me a hand? Thanks Lei

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floating points in kernel space
by mohit verma Jan. 21, 2011

Jan. 21, 2011

hi all, i read somewhere that there is no floating point arithmatic supported in the kernel space . is it true?? but the floating point registers and even floating point arithmatic units are all handled by the.........( kernel i think). thanks in advance for help........... -- ........................ *MOHIT VERMA*

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printk(KERN_x...) vs dev_x()
by Sutharshan Ramamoorthy / Prod Jan. 21, 2011

Jan. 21, 2011

Hi, I'm submitting patches to linux kernel. I'd like to know, Which is the acceptable practice to print debug messages? At some places in the code, there is no valid 'dev' pointer to pass to dev_xx() macro, at such places is it ok to use printk(KERN_XXX...)? Please let me know correct format of print messages. Thanks, Sutharsan. --------------------------------------------------------------- This message and any attachments may contain Cypress (or its subsidiaries) confidential information. If it has been received in error, please advise the sender and immediately delete this message. ---------------------------------------------------------------

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Why is flags being backed up before calling cli
by C K Kashyap Jan. 21, 2011

Jan. 21, 2011

Hi, I noticed that the flags register is being stored before doing 'cli' and then restored after calling 'sti'. - eg. in local_irq_save and local_irq_restore Can someone tell me the scenario that is being guarded against by backing up flags? Regards, Kashyap

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Regarding bi_end_io functions
by Gaurav Mahajan Jan. 21, 2011

Jan. 21, 2011

Hello all, I was writing a device mapper target. Now in that target for each bio request I set the bi_end_io field to my endio function "my_end_io". So that whenever the bio request gets complete it will call the "my_end_io" function. While registering the device mapper target we provide a structure called "target_type" to the device mapper. This structure is like this. static struct target_type my_dm_target = { .name = "my_dmt", .version = {1, 0, 0}, .module = THIS_MODULE, .ctr = dmt_ctr, .dtr = dmt_dtr, .map = dmt_map, .end_io = dmt_endio, }; It contains many other fields(Mainly function pointers). Now if you have observed the end_io field in the target_type, this is function. I was not able to figure out why there is another end_io filed is given if we can set the bi_end_io field in each bio(my_end_io). I was also not getting what's the purpose of the end_io function given in the target_type. And when this function gets called. Earlier I did not define end_io function (from target_type ) but because of that OOPS was generated. Later I dug the logs, I found that clone_endio function in dm.c is trying to access the end_io field from the target_type structure. But since function was not defined the end_io field was NULL. So it gives OOPS NULL pointer reference at that point. Looking forward for some help..... Regards, Gaurav

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