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Does a kernel developer need a hardware to do kernel development?
by Amit Kumar Oct. 1, 2016

Oct. 1, 2016

Hi, (1) I want to work on staging drivers. But I've two questions, Does a kernel developer need a hardware (e.g. board) to do kernel development? (2) I'm able to send patch using sendmail and git. I'm able to apply patch using git-am. But unable to setup mutt to download patch from this emailid. How to setup mutt to download patches? -- Regards, Amit Kumar Twitter: @freeark1 Only Numbers Can Command.

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Options for adding I2C devices and how-to
by vibnwis Oct. 1, 2016

Oct. 1, 2016

Hi there, My questions are about the options available for adding I2C devices onto existing single board computers, such as Panda Board or Raspberry Pi. Later then I would ask how to get it done. By far, I have found out the following options. Correct me if I am wrong as my understanding s still hazy. 1. BitBanging method. That is by connecting it to existing unused GPIOs. Need to create a Bitbanging client driver for the device with the two GPIOs for SDA, SCLK respectively 2. Use existing allocated I2C Pins. Assuming the kernel driver for the device is already available, then simply run make menuconfig to configure to use the right I2c device. However, if the driver is not available. One needs to create a new client driver. if up to now I am still not wrong, then I have a few questions. a) what address is it and how to specify one for the new device? would like wise to use the existing allocated addresses which are not being used due to non-existence of those I2C devices on the system? b) if somehow, the new I2C device has somewhat similar architecture with the existing supporter I2C devices, would it wise to use it instead of developing a new client driver? I am trying to say that would it wise to trial and error some of the existing supporting driver if they are compatible. Only after testing then decide if new driver development is needed. Is it the right thing to do? 3. Writing/using user mode I2c driver. Feel free to add any comments or suggestions. Thank you in advance. Best regards, Lim

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How to disable building of -dbg Debian package?
by Aleksander Alekseev Sept. 30, 2016

Sept. 30, 2016

Hello. I'm building Linux kernel like this: ``` cp /boot/config-$(uname -r) ./.config make olddefconfig make -j4 deb-pkg LOCALVERSION=-custom ``` Resulting files are (for 4.7.0 kernel): ``` 966694 linux-firmware-image-4.7.0-custom_4.7.0-custom-1_amd64.deb 10316460 linux-headers-4.7.0-custom_4.7.0-custom-1_amd64.deb 45639036 linux-image-4.7.0-custom_4.7.0-custom-1_amd64.deb 471400164 linux-image-4.7.0-custom-dbg_4.7.0-custom-1_amd64.deb 851664 linux-libc-dev_4.7.0-custom-1_amd64.deb ``` Compilation takes about an hour and most of this time is spent on creating a -dbg package which I don't install anyway. Frankly I don't think this package is very useful since Linux kernel can't be built with -O0 option [1]. Is it possible to disable building of this package? [1] https://lists.kernelnewbies.org/pipermail/kernelnewbies/2016-August/016687.… -- Best regards, Aleksander Alekseev

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problem init_mm undefined on arm
by Oscar Salvador Sept. 30, 2016

Sept. 30, 2016

Hi! While testing a module on arm platforms, I got an error which disturbed me. In my module I'm using pgd_offset_k [ http://lxr.free-electrons.com/source/arch/x86/include/asm/pgtable.h#L720] and this macro is working for x86 and x86_64. For arm platforms this macro is also defined here: http://lxr.free-electrons.com/source/arch/arm/include/asm/pgtable.h#L182 but I get this error while compiling the module on arm board: WARNING: "init_mm" [module] undefined! init_mm is first defined in http://lxr.free-electrons.com/source/mm/init-mm.c#L16 and then "exported" in http://lxr.free-electrons.com/source/include/linux/sched.h#L2558 (I'm including this header) Anyone knows how could I use pgd_offset_k in my module running on arm? Thank you very much

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Sending Patches using official Mail id
by Raul Piper Sept. 29, 2016

Sept. 29, 2016

Hi, How can I send the patches to the kernel mainline using official mail id using git-send? I am using microsoft exchange server and outlook as a client.What configuration i have to do on my linux or WIndows PC development machine. I have read about the IMAP configuration but not sure how to achieve it.Can someone please post the full details. Documentation/email-client.txt doesn't talk anything about the Microsoft Exchange server. Or using my gmail id would be the last resort? Thanks in advance ! Regards, Rp

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Re: Sending Patches using official Mail id
by Raul Piper Sept. 29, 2016

Sept. 29, 2016

On Fri, Sep 30, 2016 at 12:37 AM, Giedrius Statkevičius <giedrius.statkevicius(a)gmail.com> wrote: > On Thu, Sep 29, 2016 at 10:02 PM, Raul Piper <raulpblooper(a)gmail.com> wrote: >> Hi, >> How can I send the patches to the kernel mainline using official mail >> id using git-send? >> I am using microsoft exchange server and outlook as a client.What >> configuration i have to do on my linux or WIndows PC development >> machine. >> I have read about the IMAP configuration but not sure how to achieve >> it.Can someone please post the full details. >> Documentation/email-client.txt doesn't talk anything about the >> Microsoft Exchange server. >> Or using my gmail id would be the last resort? >> Thanks in advance ! >> Regards, >> Rp >> > (oops, replying to all now) > > `git send-email` is very handy. I think you should read the corresponding > manual page. It even has nice, very relevant examples to you as a kernel > developer. have you tried it using a corporate email id not the gmail id? which Exchange server you have used?You do it on windows or linux?

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insmod failing to insert a simple module
by Madhu K Sept. 29, 2016

Sept. 29, 2016

Hi All, While inserting a kernel module, insmod is failing with following error. insmod: error inserting 'page_walk.ko': Invalid module format. I verified the modinfo of "page_walk.ko" it is showing version magic as : 4.0.5_rc7+ SMP mod_unload modversions 686 what does "mod_unload" mean here? Thanks, Madhu

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My recent spam on the lists.
by Raymond Jennings Sept. 29, 2016

Sept. 29, 2016

I don't know why but claws decided to crap itself and spam everyone with half-typed versions of the same message. My internet was flaking out at the time too. Anyone know what happened, and any ideas for a more stable client that doesn't half-ass a message in multiple spammy chunks? Also, is it anything to do with gmail's SMTP?

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CodingStyle indentation and alignment
by Laurence Rochfort Sept. 27, 2016

Sept. 27, 2016

Hi all, I've read Documentation/CodingStyle and it states to use 8 character tabs. Reading several USB driver files including drivers/usb/usb-skeleton.c, I see that multi-line lists of argument and operands are often aligned on top of each other using a mixture of tabs and spaces. checkpatch doesn't complain about the mixture. For instance from usb-skeleton.c: static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id) uses two tabs and 6 spaces, not just tabs like: static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id) or static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id) Is a mixture of tabs and spaces acceptable if it enhances readability? If not, which of the tabs-only forms is correct? Similarly, what about assignment alignment in structs? Cheers, Laurence.

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Scheduling of interrupt
by Er Krishna Sept. 27, 2016

Sept. 27, 2016

Hi All, I am asking below question for understanding. Pls help me to understand this: 1. How does APIC schedule interrupt on particular core ? How does Apic takes a decision that first few interrupt will be schedule on Core 0 and remaining for load balancing will be schedule on different core ? What are the advantage of scheduling interrupt always on core 0 w.r.t Cache hot and all ? 2. Is it possible that incoming interrupt can be scheduled on particular core rather than core 0 ? What is the configuration option or api is available for that inside kernel or in user space ? Thanks, Krishna

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