January 2013 - kernelnewbies@kernelnewbies.org

Please help me communicating with wiz220io device
by laliteshwar yadav Jan. 19, 2013

Jan. 19, 2013

Hi All, I have written a raw socket to communicate with the device. It is not responding. I am setting every digital o/p port to high and through raw socket, i want to toggle them. It is not responding at all. my-ip 172.28.76.134 port 5000 module ip 172.28.77.50 port 8080 I have WIZ220IO REV1.O with me i send data as 57 49 5A 32 32 30 4F 00 00 00 AC 1C 4D 32 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 Please help me. Thnking you in advance.. lalit

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Re: why is this result ?
by horseriver Jan. 18, 2013

Jan. 18, 2013

On Sat, Jan 19, 2013 at 09:15:23AM +0100, Jędrzej Dudkiewicz wrote: > >> Because it's not possible to have an object with nonzero size. The > >> address of every object must be unique, so they have to be separated by > >> one byte anyway. > > > > thanks! > > Here I do not define a object of type A ,just do sizeof operation to a A struct ,not a specified object. > > So if I defined A a , does sizeof(a) have the same mean with sizeof(A) ? > > what does the sizeof operator essentially? > > Yes, sizeof(a) and sizeof(A) are identical. I understand sizeof(expr) > as "tell me how many bytes I need to store result of expression expr" . When a is stored in one bytes, what is the mean or use of that byte data? > -- > Jędrzej Dudkiewicz > > I really hate this damn machine, I wish that they would sell it. > It never does just what I want, but only what I tell it.

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working of fork and exec
by Niroj Pokhrel Jan. 18, 2013

Jan. 18, 2013

Hi all, I have been using fork and exec for sometime. But I have no idea about what are the things done by the kernel when we fork or exec and how things work. How the kernel load new program and what all things are done ....... Can anybody please explain me this ? Thank you in advance.

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When does Makefile init the variables like KBUILD_OUTPUT
by Bin Wang Jan. 18, 2013

Jan. 18, 2013

Hi, all The kernel Makefile init the variables like KBUILD_OUTPUT outside any target's make process. But when I try to output the KBUILD_OUTPUT in the target's make process, for example, the target "help", I find it is not defined. I want to know when will it init? Thanks a lot. Bin Wang

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Best way to configure Linux kernel for a machine
by Shraddha Kamat Jan. 17, 2013

Jan. 17, 2013

I normally do the kernel configuration on my machine like this - * copy the distro configuration file to the kernel dir * make menuconfig (answer Y's/N's/M's) Normally keep return key pressed for default answers * then do the actual kernel compilation Now, I know that this is not a clean way to do the kernel compilation (although it has worked for me for thousands of times that I have compiled and successfully booted up with the kernel - without any issues - whatsoever !) But this time , I am bent upon coming up with a configuration specifically targeted to my machine. What is the best way to do this ? Also, while creating a initrd image # mkinitrd /boot/initramfs.img 3.8.0-rc3+ -f ERROR: modinfo: could not find module ipt_MASQUERADE ERROR: modinfo: could not find module iptable_nat ERROR: modinfo: could not find module nf_nat ERROR: modinfo: could not find module snd_hda_codec_intelhdmi ERROR: modinfo: could not find module joydev I got the above errors - I know how to resolve these errors , but want to understand why in the first place mkinitrd should complain in the first place ?? Thanks list for help for all these years. -- Shraddha

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what is the function of tcp_prequeue ?
by horseriver Jan. 17, 2013

Jan. 17, 2013

hi: what is the function of tcp_prequeue ? thanks!

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Is "make rpm-pkg" and "make binrpm-pkg" same?
by Bin Wang Jan. 17, 2013

Jan. 17, 2013

Hi, I build the kernel with "make rpm-pkg" and "make binrpm-pkg". The "make help" shows: rpm-pkg - Build both source and binary RPM kernel packages binrpm-pkg - Build only the binary kernel package But except the different process, the RPMs I got seems same. I look the kernel.spec and binkernel.spec, it seems same, too. I'm wonder does rpm-pkg really build source? Thanks, Bin Wang

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what is the function of do_softirq() ?
by horseriver Jan. 16, 2013

Jan. 16, 2013

hi: what is the function of do_softirq()? It is called by ksoftirqd() ,which is setup by : kernel_thread(ksoftirqd, hcpu, CLONE_KERNEL) ; thanks!

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Kernel-space flirting with user-space
by Simon Jan. 16, 2013

Jan. 16, 2013

Hi there, I'm rather new to kernel development, but I am somewhat experienced with Linux, kernel compilation, etc. I'm just passed writing a helloworld module, dummy filesystem (ramfs wrapper) and proc entry. I would like to know how communication between kernel & user-space is done (the standard) for a high number of tiny and large messages going in both directions (large messages would need to be transfered incrementally, in chunks, can be sequential or random access). I plan on developping a network filesystem. I would appreciate if someone could clarify where I'm wrong and confirm where I'm right, and ideally suggest some vocabulary, source files to lookup, online docs or even books. The minimum you can give will be most appreciated! =) Firstly, I was wondering if it would be possible to implement the filesystem entirely as a kernel module. I would need TCP/UDP sockets. I think this is really not the recommended approach, but an advantage I see is it could be used to mount the root filesystem before calling init (that would be before user-space exists, right?). On the other hand, separating the work to have a program/daemon in user-space do the communication and processing would allow me to write that part in C++ (which I personally prefer). Secondly, I wonder how I can "bind" a user-space program/daemon with the kernel-space of the module. Using procfs: It seems technically possible to achieve my goal with it, but I feel this would not be the standard approach. I would rather keep it for live config & live status reporting. Using sysfs: I've read too much misleading information that I'm not sure anymore what it's for or even if it's still used or deprecated! Can someone clarify? It looks technically identical to procfs, but it's mission is a different one, correct? Using pipes: This may be a good way, but again, I'm not sure if it's the standard way. Using IPC: As far as I understand, IPC would be the way if we'd be talking of two threads within the same process, or at least within kernel-space. Though I am likely to be wrong. Using a char device: It seems technically possible as well, but it may be difficult to deal with if I ever have more than one user-space process. Using a block device: My file system works with files and their metadata, but not with blocks, so this is not suitable. Though it might be a nice experiment to build a network block device containing an ext2 filesystem (which I think would be similar to iSCSI). Using net interface: Not applicable. And an experiment to try to make it applicable doesn't even seem remotely fun. ;) I've seen the functions copy_to/from_user() or something like that, but I haven't seen the user-space counter-part of these. I think this may actually be the best approach by far, but I really lack info/docs to go that way. The truly best way might be to use shared memory to avoid copying data internally, but I haven't looked into that much yet. Finally, is it possible/correct/standard to do something similar to the following for the local kernel & user-space communication? (I haven't reviewed the syntax, so take it as some kind of pseudo-code!) struct foo {...} outgoingFoo; // foo contains no pointers, so it is of a fixed size always. fwrite(&outgoingFoo, 1, sizeof(outgoingFoo), output); [...then on the other end...] if(sizeof(fread( buffer, 1, buffer_size, input); struct foo * incomingFoo = (struct foo *) buffer; Regards, Simon

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Re: Best way to configure Linux kernel for a machine
by Leo Jan. 16, 2013

Jan. 16, 2013

Sorry, my email client somewhat broke... On 16 January 2013 21:22, Leonid V. Fedorenchik <leonidsbox(a)gmail.com>wrote: > On Wed, 16 Jan 2013 17:47:08 +0530 > Shraddha Kamat <sh2008ka(a)gmail.com> wrote: > > > I normally do the kernel configuration on my machine like this - > > > > * copy the distro configuration file to the kernel dir > > * make menuconfig (answer Y's/N's/M's) Normally keep return key > > pressed for default answers > > * then do the actual kernel compilation > > > > > > Now, I know that this is not a clean way to do the kernel compilation > > (although it has worked for me for thousands of times that I have > > compiled and successfully booted up with the kernel - without any > > issues > > - whatsoever !) > > > > But this time , I am bent upon coming up with a configuration > > specifically targeted to my machine. What is the best way to do this ? > > > > Although I am not professional in this, I would suggest to read Linux > Kernel in a Nutshell by Greg Kroah-Hartman which is available online > at http://www.kroah.com/lkn/ . Specifically, Chapter 8 provides good > details about custom configurations. > > Hope this helps. > > > > > Also, while creating a initrd image > > > > # mkinitrd /boot/initramfs.img 3.8.0-rc3+ -f > > ERROR: modinfo: could not find module ipt_MASQUERADE > > ERROR: modinfo: could not find module iptable_nat > > ERROR: modinfo: could not find module nf_nat > > ERROR: modinfo: could not find module snd_hda_codec_intelhdmi > > ERROR: modinfo: could not find module joydev > > > > I got the above errors - I know how to resolve these errors , but want > > to understand why in the first place mkinitrd should complain in the > > first place ?? > > > > Thanks list for help for all these years. > > > > -- Shraddha > > > > > > > > _______________________________________________ > > Kernelnewbies mailing list > > Kernelnewbies(a)kernelnewbies.org > > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > Leonid V. Fedorenchik >

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