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git send-email
by Tobin Harding May 22, 2016

May 22, 2016

Workflow - $ git format-patch -s -1 add patch comment then $ git send-email Question please - Who should the email be sent to without having a 'To' address repeated in the CC field generated by `git send-email`. To rephrase the question: git send-email CC's everyone who may be interested according to get_maintainers.pl. Will I annoy people if I address them in the To field as well as the CC field. Thank you in advance for your time, Tobin Harding.

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what is the point of "dt-bindings" symlinks under some arches?
by Robert P. J. Day May 22, 2016

May 22, 2016

i'm curious about the value of the small number of "dt-bindings" symlinks under some architectures that all simply link to the top-level include/dt-bindings/ directory: $ find . -name dt-bindings -exec ls -ld {} \; lrwxrwxrwx. 1 rpjday rpjday 34 Apr 26 13:07 ./arch/cris/boot/dts/include/dt-bindings -> ../../../../../include/dt-bindings lrwxrwxrwx. 1 rpjday rpjday 34 Apr 25 10:58 ./arch/powerpc/boot/dts/include/dt-bindings -> ../../../../../include/dt-bindings lrwxrwxrwx. 1 rpjday rpjday 34 Apr 25 10:57 ./arch/metag/boot/dts/include/dt-bindings -> ../../../../../include/dt-bindings lrwxrwxrwx. 1 rpjday rpjday 34 Apr 25 10:57 ./arch/arm64/boot/dts/include/dt-bindings -> ../../../../../include/dt-bindings lrwxrwxrwx. 1 rpjday rpjday 34 Apr 25 10:57 ./arch/arm/boot/dts/include/dt-bindings -> ../../../../../include/dt-bindings lrwxrwxrwx. 1 rpjday rpjday 34 Apr 25 10:57 ./arch/mips/boot/dts/include/dt-bindings -> ../../../../../include/dt-bindings drwxrwxr-x. 26 rpjday rpjday 4096 Apr 26 13:07 ./include/dt-bindings $ normally, i expect to see setups like that in cases where, historically, an architecture kept track of its own content and, at some point, it was centralized, so the previous directory (whatever it contained) was simply replaced by a symlink. but even without that arch-specific symlink, wouldn't the top-level include/dt-bindings/ directory be searched, anyway? or maybe not, i guess i'll check the Makefile to see if it would be. thoughts? given that all those symlinks are absolutely identical, couldn't they all just be removed? 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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Management of duplicate commits in public repository
by William Breathitt Gray May 21, 2016

May 21, 2016

I'm curious how subsystem maintainers typically handle duplicate commits in their public subsystem repositories. I'm referring to commits which appear originally in their branch, but are cherry-pick'd to another subsystem maintainer's repository, and then later merged back in; this leads to the same textual changes appearing as two distinct commits after the merge. In my workflow, I typically rebase against the public repository before I submit my patches to the subsystem maintainer. In this scenario, the rebase drops commits which do not produce textual changes in my tree. Thus, I never have duplicate commit messages in my private repository. However, a subsystem repository is public, so subsystem maintainers typically merge new releases of the Linux kernel, rather than rebase, since history should not be written. If merges are continually performed, will the subsystem repository not gradually accumulate duplicate commits over time? Are the duplicate commits simply accepted as the cost of operating a public repository, or do the subsystem maintainers make an effort to remove them before the merge? William Breathitt Gray

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if block style when condition spams to multiple lines.
by Daniel. May 20, 2016

May 20, 2016

What is the preferred way to ident if statement when the condition spams to multiple lines, ex: if (cond1 && cond2 && cond3) { ... ... } or if (cond1 && cond2 && cond3) { ... ... } or if only one statement inside body if (cond1 && cond2 && cond3 ... Also, usualy, I align the remaining lines from codition to one column after the parenthesis that starts the condition and usually I need spaces to do that. Is that okay? With no spaces would be: if (cond1 && cond2) { ... Regards, -- *"Do or do not. There is no try"* *Yoda Master*

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TEA5767 FM driver issue
by Aric May 18, 2016

May 18, 2016

hi, I'm working on using fm tea5767 module. But, I found it already have driver, in drivers/media/common/tuners/tea5767.c . I resiger a i2c board info in arch/arm/mach-xxxx, but only found a i2c device in /sys/bus/i2c/devices/0-0060. The driver and device not going to match !! Anyonre can help ? Seems the driver was not called, how to trigger the driver match procedure ? Thx!! /BRs

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how to properly "export" a new header file to user space?
by Robert P. J. Day May 18, 2016

May 18, 2016

just want to make i'm using the new UAPI infrastructure properly, since i remember the old days of stuffing "header-y" all over the place in Kbuild files. say i want to add a new driver to the kernel, so i create the directory /drivers/rday, and add some code and i create a header file, "rday1.h", that will be used by both my kernel code *and* needs to be included by user space code as well. normally, i could just leave that header file in that directory, and let the source file use: #include "rday1.h" but if i want that header file visible in user space, as i read it, i can create a new directory at the top level of the kernel source: include/uapi/rday/ inside of which i can place the file "rday1.h", which has the following consequences. first, given this code in the top-level Makefile: # Use USERINCLUDE when you must reference the UAPI directories only. USERINCLUDE := \ -I$(srctree)/arch/$(hdr-arch)/include/uapi \ -Iarch/$(hdr-arch)/include/generated/uapi \ -I$(srctree)/include/uapi \ -Iinclude/generated/uapi \ -include $(srctree)/include/linux/kconfig.h # Use LINUXINCLUDE when you must reference the include/ directory. # Needed to be compatible with the O= option LINUXINCLUDE := \ -I$(srctree)/arch/$(hdr-arch)/include \ -Iarch/$(hdr-arch)/include/generated/uapi \ -Iarch/$(hdr-arch)/include/generated \ $(if $(KBUILD_SRC), -I$(srctree)/include) \ -Iinclude \ $(USERINCLUDE) my own kernel code should now use the include directive: #include <rday/rday1.h> which should properly locate that header file. and, second, user space code can use the same directive as long as i extend the user space header file search path to include "<kernel-source-tree/include/uapi", correct? am i thinking about this the right way? i'm using the model under drivers/mtd, where one sees examples like: nand/fsmc_nand.c:#include <mtd/mtd-abi.h> ubi/cdev.c:#include <mtd/ubi-user.h> with directory contents: $ tree include/uapi/mtd include/uapi/mtd ├── inftl-user.h ├── Kbuild ├── mtd-abi.h ├── mtd-user.h ├── nftl-user.h └── ubi-user.h $ i also note that include/uapi/mtd includes header files meant to be included *only* from user space, such as mtd-user.h, which is fine. so is this the correct approach? or am i missing something easier? rday p.s. i also note the Kbuild file "include/uapi/mtd/Kbuild", for use if i want to export those headers with: $ make headers_install but if i don't want to export my own header files that way, i see no need to add a Kbuild file, at least not for the moment. thoughts? -- ======================================================================== 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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Run queue corruption issue
by Jerrin Shaji George May 18, 2016

May 18, 2016

Hi All, I wanted help with a piece of code that I have been working on. Please see - https://gist.github.com/jerrinsg/333e584d1f65dc95b9f13b61dcebdaa7 I have written two function, migrate_to and migrate_back. migrate_to is used to remove a process from the run queue, and migrate_back is used to insert this process back into the run queue. The gist is from a taken from a larger project, where we are working on building a mechanism to support thread migration across heterogeneous processors. migrate_to_call() will be called by a thread which wants to remove itself from the run queue (hence, it will pass the current task struct as the migration argument). Once the other processor completes execution of the assigned task, it will interrupt the main processor, which runs an interrupt handler, which in turn calls the migrate_back_call() function. It passes the task struct of the process that was removed from the run queue earlier to this function. This mechanism works fine the first few times, but when this process is repeated many times in a loop, I am seeing a run queue corruption: https://gist.github.com/jerrinsg/0ab09cd435d8d2cb6ae692c7e6f4f26b Is there anything wrong in the process dequeue or enqueue function that I have written? Please help! Kernel used: Linux 3.13 Thanks, Jerrin

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Re: can anyone tell me which function to call to pause the kernel
by Mulyadi Santosa May 18, 2016

May 18, 2016

On Mon, May 16, 2016 at 7:36 AM, walkerlala <ablacktshirt(a)gmail.com> wrote: > On 2016年05月16日 01:36, Mulyadi Santosa wrote: > >> >> >> On Thu, May 12, 2016 at 9:55 PM, walkerlala <ablacktshirt(a)gmail.com >> <mailto:ablacktshirt@gmail.com>> wrote: >> >> I successfully insert some function into the kernel code and make it >> execute when the kernel start up, but I just can't make the kernel >> stop >> executing. Are there any functions which can pause the kernel so that >> I >> prompt the user, and let the user input a command(maybe a comment to >> display the current time. Something like a shell would do) and >> interact ? >> (I had checked the "sys_***" functions in this page: >> http://docs.cs.up.ac.za/programming/asm/derick_tut/syscalls.html >> but just can't find a proper one ) >> >> _______________________________________________ >> Kernelnewbies mailing list >> Kernelnewbies(a)kernelnewbies.org <mailto: >> Kernelnewbies(a)kernelnewbies.org> >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >> >> >> Hi... >> >> sounds like what kgdb does. But not sure if it is still maintained or not. >> >> btw, kernel can not be paused, actually. if you really need that, you >> need to run linux kernel inside virtual machine and pause the virtual >> machine. But doing that, you will also pause user space too :) >> >> -- >> regards, >> >> Mulyadi Santosa >> Freelance Linux trainer and consultant >> >> blog: the-hydra.blogspot.com <http://the-hydra.blogspot.com> >> training: mulyaditraining.blogspot.com < >> http://mulyaditraining.blogspot.com> >> > > Hi, thanks for reply. > > I know using a debugger or virtual machine would help a little bit, but > that's not interactive any more. What I want is just a shell-like > "interactive" kernel (may be I am a little naive to think that ?) > > Why the kernel cannot be stopped ? I think, now that if the kernel can be > interrupted, then why can't it be stopped by some mechanisms ? > > Regards, > > Hi... please add kernelnewbies to cc: list too next time :) Kernel can't be stopped, because it's actually servicing event mostly generated by hardware (interrupts etc) or user space (syscall etc). So unless you stop these two aspects to raise events, basically kernel will still do its works. -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com

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How to locally maintain an end-of-life kernel branch?
by Michael Harless May 17, 2016

May 17, 2016

Hi, Sorry if this is covered somewhere, I haven't been able to find much yet in my searches. I'm working on a project using the LTS 3.14 kernel, but I'll need to be supporting it long after official support ends on kernel.org for the branch. Are there any pointers or suggestions on how to monitor for security and bug fixes that I'll need to pull in and merge myself? I'm watching the lkml for patches and trying to follow the latest changes via git, but I'm sure that I'll miss things in all of the traffic. Thanks! --Mike

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Kernel memory
by Ronit Halder May 17, 2016

May 17, 2016

Hi, Where in the memory kernel is located in the boot time? regards, Ronit

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