April 2018 - kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

Add IIO example to the kernelnewbies wiki
by Gaston Gonzalez Feb. 21, 2019

Feb. 21, 2019

Hi, I'm testing an AD7746 eval board using a Diolan DLN-2 adapter. I wrote some basic notes about the installation an instanciation process for my own use. But then I thought it could be useful for someone else. So maybe I could put this in the kernel newbies page under the IIO section? If you think is worth it, I would be glad to add it to the wiki page. Best regards, Gaston Notes: The setup ========= AD7746-EVAL BOARD --> Diolan DLN-2 Adapter --> Thinkpad T430 The connection between the AD7746 eval board and adapter is as detailed in [2] I2C Interface Configuration Options, External connection (pag 4). The connection between Diolan DLN-2 and the T430 is USB straighforward. Drivers ======= Both in mainline kernel: - Diolan DLN-2 driver: I2C_DLN2 (prompt Diolan DLN-2 USB I2C adapter) Loc: drivers/i2c/busses/ - AD7746: AD7746 Loc: drivers/staging/iio/cdc/ Bus of interest =============== $ sudo i2cdetect -l We get something like: ... i2c-10 i2c dln2-i2c-1-1.2:1.0-0 I2C adapter ... So our bus is the number 10. Getting the address =================== $ sudo i2cdetect -y -r 10 We get something like: 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- -- -- -- -- -- -- 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 40: -- -- -- -- -- -- -- -- 48 -- -- -- -- -- -- -- 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 70: -- -- -- -- -- -- -- -- 3. Device instantiation: # echo add7746 0x48 > /sys/bus/i2c/devices/i2c-10/new_device We must see something like: $ cd /sys/bus/i2c/devices/i2c-10/10-0048/ $ ls driver iio:device0 modalias name power subsystem uevent $ cd iio:device0 $ ls dev in_capacitance-capacitance_calibbias in_capacitance0_calibbias_calibration in_capacitance-capacitance_sampling_frequency in_capacitance0_calibscale in_capacitance-capacitance_scale in_capacitance0_calibscale_calibration in_capacitance_sampling_frequency in_capacitance0-capacitance2_calibscale in_capacitance_sampling_frequency_available in_capacitance0-capacitance2_offset in_capacitance_scale in_capacitance0-capacitance2_raw in_temp0_input in_capacitance0_offset in_temp1_input in_capacitance0_raw in_voltage0_calibscale_calibration in_capacitance1_calibbias_calibration in_voltage0_raw in_capacitance1_calibscale in_voltage1_supply_raw in_capacitance1_calibscale_calibration in_voltage_sampling_frequency in_capacitance1-capacitance3_calibscale in_voltage_sampling_frequency_available in_capacitance1-capacitance3_offset in_voltage_scale in_capacitance1-capacitance3_raw name in_capacitance1_offset power in_capacitance1_raw subsystem in_capacitance_calibbias uevent Checking the permits: $ ll -r--r--r-- 1 root root 4096 mar 31 09:57 dev --w------- 1 root root 4096 mar 31 09:57 in_capacitance0_calibbias_calibration -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance0_calibscale --w------- 1 root root 4096 mar 31 09:57 in_capacitance0_calibscale_calibration -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance0-capacitance2_calibscale -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance0-capacitance2_offset -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance0-capacitance2_raw -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance0_offset -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance0_raw --w------- 1 root root 4096 mar 31 09:57 in_capacitance1_calibbias_calibration -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance1_calibscale --w------- 1 root root 4096 mar 31 09:57 in_capacitance1_calibscale_calibration -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance1-capacitance3_calibscale -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance1-capacitance3_offset -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance1-capacitance3_raw -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance1_offset -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance1_raw -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance_calibbias -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance-capacitance_calibbias -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance-capacitance_sampling_frequency -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance-capacitance_scale -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance_sampling_frequency -r--r--r-- 1 root root 4096 mar 31 09:57 in_capacitance_sampling_frequency_available -rw-r--r-- 1 root root 4096 mar 31 09:57 in_capacitance_scale -rw-r--r-- 1 root root 4096 mar 31 09:57 in_temp0_input -rw-r--r-- 1 root root 4096 mar 31 09:57 in_temp1_input --w------- 1 root root 4096 mar 31 09:57 in_voltage0_calibscale_calibration -rw-r--r-- 1 root root 4096 mar 31 09:57 in_voltage0_raw -rw-r--r-- 1 root root 4096 mar 31 09:57 in_voltage1_supply_raw -rw-r--r-- 1 root root 4096 mar 31 09:57 in_voltage_sampling_frequency -r--r--r-- 1 root root 4096 mar 31 09:57 in_voltage_sampling_frequency_available -rw-r--r-- 1 root root 4096 mar 31 09:57 in_voltage_scale -r--r--r-- 1 root root 4096 mar 31 09:57 name drwxr-xr-x 2 root root 0 mar 31 09:57 power lrwxrwxrwx 1 root root 0 mar 31 09:57 subsystem -> ../../../../../../../../../../../bus/iio -rw-r--r-- 1 root root 4096 mar 31 09:57 uevent 4. Capacitance According to [2], the capacitive length sensor is connected to CIN2+ and CIN2-. In the driver, the values are mapped to capacitance0. Raw values vs sensor length: Note: (+) values means the sensor was moved to the left, (-) values means the sensor was moved to the right. I.e. +1 cm means the rule was moved 1 to the left, while -1 means the rule was moved 1 cm to the right. Note2: note the raw value for -10 is 8224733, while +10 is -8224726, the difference is because when the rule is moved 10 cm to the left, the is still 2 o 3 cm of dielectric between the plates. The design is obviously thought to move the rule to the right. Length (cm) | Raw Value Cap0 ------------------------------ -10 -8224733 -9 -8224730 -8 -8224728 -7 -8224725 -6 -8224724 -5 -8224722 -4 -8224720 -3 -8224718 -2 -8224716 -1 -8224714 +0 -8224711 +1 -8224711 +2 -8224711 +3 -8224711 +4 -8224713 +5 -8224715 +6 -8224717 +7 -8224719 +8 -8224721 +9 -8224723 +10 -8224726 References ========== [1] http://www.analog.com/media/en/technical-documentation/data-sheets/AD7745_7… [2] http://www.analog.com/media/en/technical-documentation/evaluation-documenta… [3] https://i2c.wiki.kernel.org/index.php/Main_Page [4] https://kernelsense.wordpress.com/2016/01/22/achievement-unlocked-first-iio…

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Re: Kernelnewbies Digest, Vol 89, Issue 14
by Tran Ly Vu May 11, 2018

May 11, 2018

Hi, Is eudyptula challenge still alive? Thanks On 20 April 2018 at 00:00, <kernelnewbies-request(a)kernelnewbies.org> wrote: > Send Kernelnewbies mailing list submissions to > kernelnewbies(a)kernelnewbies.org > > To subscribe or unsubscribe via the World Wide Web, visit > https://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. How can I disable compile optimization in kernel for friendly > debugging, Thanks (sizel) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Thu, 19 Apr 2018 16:58:40 +0800 (CST) > From: sizel <sizel(a)163.com> > To: kernelnewbies <kernelnewbies(a)kernelnewbies.org> > Subject: How can I disable compile optimization in kernel for friendly > debugging, Thanks > Message-ID: <623d8297.8a0f.162dd208d7b.Coremail.sizel(a)163.com> > Content-Type: text/plain; charset="gbk" > > An HTML attachment was scrubbed... > URL: <http://lists.kernelnewbies.org/pipermail/kernelnewbies/ > attachments/20180419/53df7387/attachment-0001.html> > > ------------------------------ > > Subject: Digest Footer > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies(a)kernelnewbies.org > https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > ------------------------------ > > End of Kernelnewbies Digest, Vol 89, Issue 14 > ********************************************* >

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Re: how to identify kernel build in grub menu
by Alex Arvelaez May 7, 2018

May 7, 2018

On Apr 29, 2018 9:51 AM, Sumit Kumar <sumit686215(a)gmail.com> wrote: > > Hi, > > I built a kernel for the first time following this guide : > https://kernelnewbies.org/OutreachyfirstpatchSetup > > I rebooted my ubuntu machine and went to the grub menu and then chose > advanced option menu. I could see 5-6 different choices listed as Ubuntu > with different versions: > > 1. Are they all referring to some kernel build ? Yeah, check the kernel versions and you'll see that all entries are different. > 2. If so, how do I identify my build from the rest of the builds ? Is > there a way to name my build so that I can easily identify it ? There is an option to append a string to the version of the kernel. Use it to tag your kernels, you can find it by doing `make nconfig` I think it's under the "General" category(I'm paraphrasing) check the docs for the actual wording. Also after building and installing your new kernel you'll need to update your grub menu so it can detect the new kernel. Regards, Alex

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Softlockup and Hardlockup sample test module
by Ivid Suvarna May 6, 2018

May 6, 2018

Hi All, Could you please provide some sample test module for causing a Softlockup and Hardlockup in latest kernel for SMP for testing purposes. I assume there are some Kconfigs to be enabled as well for this. I had tried with the module where I put a busy loop inside spinlock but was not able to cause any lockups. Maybe this is because of SMP which schedule the job to other CPU. "How do I make a task to run on single CPU only?" I only get RCU stalls sometimes instead of softlockup when I use busy loop inside a spinlock. Is there any explanation for difference between these stalls and softlockup. Thanks, IVID

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Update required packages to compile Linux Kernel
by Jefferson Capovilla May 5, 2018

May 5, 2018

Hi, I followed the tutorial available in this link: https://kernelnewbies.org/OutreachyfirstpatchSetup and noticed that it's necessary to install three more packages during step "Install some packages". The missing packages are: *bison flex libelf-dev* Could someone please update this info there? -- -- Thanks, Jeff

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System call service routine and interrupt context
by Pritam Bankar April 30, 2018

April 30, 2018

Hi, My question is, do all the code of interrupt handler in system call gets executed in interrupt context? System calls generate software interrupts. So when I do open() syscall it we call do_sys_open() handler which will eventually call file system specific open function call. Will all this happen in interrupt context until I get open file descriptor in user land? If not when does context change? Thanks and regards, Pritam Bankar

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how to identify kernel build in grub menu
by Sumit Kumar April 29, 2018

April 29, 2018

Hi, I built a kernel for the first time following this guide : https://kernelnewbies.org/OutreachyfirstpatchSetup I rebooted my ubuntu machine and went to the grub menu and then chose advanced option menu. I could see 5-6 different choices listed as Ubuntu with different versions: 1. Are they all referring to some kernel build ? 2. If so, how do I identify my build from the rest of the builds ? Is there a way to name my build so that I can easily identify it ? My grub options looked like these : 1. https://www.google.co.in/search?q=ubuntu+grub+advanced+options&source=lnms&…: 2. https://www.google.co.in/search?q=ubuntu+grub+advanced+options&source=lnms&…: -- Thanks and Regards, Sumit

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Re: [PATCH] sched/fair: Change sched_feat(x) in !CONFIG_SCHED_DEBUG case
by Lukas Bulwahn April 23, 2018

April 23, 2018

On Fri, 20 Apr 2018, Peter Zijlstra wrote: > On Fri, Apr 20, 2018 at 06:29:07PM +0200, Philipp Klocke wrote: > > The gain is stopping a warning that clutters the output log of clang. > > Well, you should not be using clang anyway. It is known to miscompile > the kernel. > There are some advantages of having a second compiler that can compile the kernel (https://lwn.net/Articles/734071/) Some people in the kernel community and LLVM community are trying to get that to work. We also want a zero-warning policy for clang, similar to gcc. Hence, this motivates to have a look at those few clang warnings and come up with patches for them. This does not imply to make changes at any cost, and we need to determine a proper patch to either change the source code, disable the warning in the build script or annotate the file with some clang-specific pragmas. To us, a minor change in the source sounded most reasonable after looking at all three possible patches. Philipp might need another iteration, but it generally looks sound to me if we get the details flattened out. Lukas

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unable to build kernel
by Sumit Kumar April 22, 2018

April 22, 2018

Hi, I am unable to build kernel. Can anyone please help ? I am following steps from here: https://kernelnewbies.org/OutreachyfirstpatchSetup sumitsum@sumit-personal:~/Documents/linux_kernel/git/kernels/staging$ make -j3 YACC scripts/kconfig/zconf.tab.c /bin/sh: 1: bison: not found scripts/Makefile.lib:210: recipe for target 'scripts/kconfig/zconf.tab.c' failed make[2]: *** [scripts/kconfig/zconf.tab.c] Error 127 make[2]: *** Waiting for unfinished jobs.... LEX scripts/kconfig/zconf.lex.c /bin/sh: 1: flex: not found scripts/Makefile.lib:195: recipe for target 'scripts/kconfig/zconf.lex.c' failed make[2]: *** [scripts/kconfig/zconf.lex.c] Error 127 Makefile:525: recipe for target 'syncconfig' failed make[1]: *** [syncconfig] Error 2 make: *** No rule to make target 'include/config/auto.conf', needed by 'include/config/kernel.release'. Stop. make: *** Waiting for unfinished jobs.... -- Thanks and Regards, Sumit

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when to use make olddefconfig
by Sumit Kumar April 22, 2018

April 22, 2018

Hi, I was going through this link : https://kernelnewbies.org/OutreachyfirstpatchSetup , and came across the make olddefconfig cmd. The explanation on the web page is very confusing. Can anyone please explain in simpler way when "make olddefconfig" cmd is intended to be used ? The webpage says this : If you need to make any changes to your configuration, run this command to silently update any new configuration values to their default. -- Thanks and Regards, Sumit

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