October 2016 - kernelnewbies@kernelnewbies.org

Why I can't find PCIe Device
by Muni Sekhar Oct. 25, 2016

Oct. 25, 2016

Hi All, I am using Adlink COM Express Type 2 module and American Megatrends Inc BIOS. I put the AMD Radeon Graphics card in the PCIe slot, but it’s not detected(lspci does not show this device) Any idea, what might be the reason for not detecting the PCIe graphics card? Is there any BIOS settings related to PCIe needs to be checked? -- Thanks, Sekhar

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What subsystem!?
by Daniel. Oct. 25, 2016

Oct. 25, 2016

Hi everybody, I've been studying linux for some time now. I still see my self as an begginer, but that's not a bad thing. I struggling to decide what subsystem to focus right know. I have three options and would like to know what people think about, since listening (or reading) other people aways help me to decide. My options are: i. Memory ii. Network iii. Filesystems / Disk cache Today I'm working on embedded market and have a crush on ARM architecture. I have absolute no knowledge on (i), some fundations (in userspace) on (ii) and nothing but mkfs experience on (iii). LoL. The second question is: What are the (market) applications of these expertise? I know that (ii) will be huge part ot IoT and IIoT. And the (iii) can be used on database tunning for example. (i) seem just f******* cool to me. When I say (market) please, do not get me wrong. The jobs on kernel are not popping out (especially on Brazil) like the Java & Big Data ones, I still have to eat, but I'm not willing to move from my passions(kernel-dev) for money. Thanks in advance and regards to everybody! -- "Do or do not. There is no try" Yoda Master

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Device Tree
by Madhu K Oct. 25, 2016

Oct. 25, 2016

Hi All, This is to understand how Device tree works in linux kernel. If in case Device tree is not there, where and how to pass the hardware information to the linux kernel. Does all embedded systems contains Device tree? Regards, Madhu

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dirty page throttling?
by Raymond Jennings Oct. 25, 2016

Oct. 25, 2016

I was told that it had something to do with balance_dirty_pages(), but how do I allow my system to dirty as much data as it wants to? I'm running a world simulation with a lot of I/O churn, and I'm trying to get my system to 1. Let it dirty as much data as it wants to, even booting out anon or filecache to do so up to /proc/sys/vm/dirty_ratio 2. When it wants to writeback, don't throttle how much gets moved from Dirty to Writeback, but basically dump the entire load in one go and let the I/O scheduler digest it.

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Is that possible to implement a single machine with heterogeneous architecture.
by Douglas Su Oct. 21, 2016

Oct. 21, 2016

Hello everyone, Is that possible to install multiple CPUs which have different architecture on a single machine? For example, on a single machine with two different cpu sockets for X86 and MIPS cpu respectively, and these two cpus are inter-connected with some sorts of bus (PCI or other advanced buses). If it is possible, Is this machine still SMP? What will lscpu (or cat /proc/cpuinfo) dump? Thx!

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QEMU?
by Kenneth Adam Miller Oct. 19, 2016

Oct. 19, 2016

So, we can use qemu within our development system here, but the problem is we have something that is a bit specialized in that the machines talk to one another over a special interface. It's a bit like named pipes, and to our applications, named pipes are a sufficient interface to test over. In any case, I was wondering, does anybody know of a way to share memory between two QEMU instances? Or even to communicate between two instances?

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Re: Kernelnewbies Digest, Vol 71, Issue 22
by Sukanya Ch Oct. 19, 2016

Oct. 19, 2016

Hi Wenda Ni, Please go through the following link to enable debugging output.Seems you have missed enabling DEBUG in Makefile. Hope it will help you. https://www.kernel.org/doc/local/pr_debug.txt *CFLAGS_[filename].o := -DDEBUG* *With Best Regards,* Sukanya Ch Software Engineer VVDN Technologies Pvt Ltd *Cell : *+91 9551955031 | *Skype :* sukanya.chinthamreddy On Tue, Oct 18, 2016 at 7:44 PM, <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. kernel loglevel (Wenda Ni) > 2. Re: kernel loglevel (Wenda Ni) > 3. Re: kernel loglevel (Joel Fernandes) > 4. Re: kernel loglevel (Thibaut SAUTEREAU) > 5. Re: kernel loglevel (Wenda Ni) > 6. Fw: TPS65910 Regulator Isuue (Amit Mahadik) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 17 Oct 2016 19:17:32 -0400 > From: Wenda Ni <wonda.ni(a)gmail.com> > Subject: kernel loglevel > To: kernelnewbies(a)kernelnewbies.org > Message-ID: > <CAEnvTt0RRDWtMD=VxVpuhiiJ+MRX2g3WiTgXkA-M5GGaTMyB-g@ > mail.gmail.com> > Content-Type: text/plain; charset=UTF-8 > > Dear all, > > I am working on a kernel module that incorporate both pr_debug and > pr_warn. I would like to see pr_debug messages from dmesg. > > What I followed is to specify kernel parameter by saying "loglevel=7". > This can be seen confirmed from /proc/cmdline. But still, I donot get > pr_debug level messages either from dmesg or from /var/log/messages. I > also tried echo 7 > /proc/sys/kernel/printk. It does not return what I > expect, either. > > Let me know what I am missing. Thank you very much in advance. > > Cheers, > > Wenda Ni, Ph.D. > > > > ------------------------------ > > Message: 2 > Date: Mon, 17 Oct 2016 19:47:14 -0400 > From: Wenda Ni <wonda.ni(a)gmail.com> > Subject: Re: kernel loglevel > To: Thibaut SAUTEREAU <thibaut.sautereau(a)telecom-sudparis.eu> > Cc: kernelnewbies(a)kernelnewbies.org > Message-ID: > <CAEnvTt3oh+tuhKCwho8eZd5VmJfuXdcmWGpUpsji > H2wWSFpWvg(a)mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > Thank you so much, Thibaut. I have spotted the source-code logic in > include/linux/prink.h > > Cheers, > > Wenda Ni, Ph.D. > > > > On Mon, Oct 17, 2016 at 7:41 PM, Thibaut SAUTEREAU < > thibaut.sautereau(a)telecom-sudparis.eu> wrote: > > On Mon, Oct 17, 2016 at 07:17:32PM -0400, Wenda Ni wrote: > >> Dear all, > >> > >> I am working on a kernel module that incorporate both pr_debug and > >> pr_warn. I would like to see pr_debug messages from dmesg. > >> > >> What I followed is to specify kernel parameter by saying "loglevel=7". > >> This can be seen confirmed from /proc/cmdline. But still, I donot get > >> pr_debug level messages either from dmesg or from /var/log/messages. I > >> also tried echo 7 > /proc/sys/kernel/printk. It does not return what I > >> expect, either. > >> > >> Let me know what I am missing. Thank you very much in advance. > >> > >> Cheers, > >> > >> Wenda Ni, Ph.D. > >> > >> _______________________________________________ > >> Kernelnewbies mailing list > >> Kernelnewbies(a)kernelnewbies.org > >> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > > Hello Wenda, > > > > I encountered the same issue a while ago. > > As stated here: http://elinux.org/Debugging_by_printing > > pr_debug is replaced with an empty statement unless the kernel is > compiled > > with DEBUG. So if you just want to play with printing kernel debug logs, > > just define the DEBUG macro in your module source file for testing. > > > > I also observed that without a new line character at the end of the > string > > passed to pr_debug, I could not find the log line in dmesg output. Not > sure > > where this comes from. > > > > -- > > Thibaut SAUTEREAU >

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hello kernelnewbies
by Anders Lind Oct. 19, 2016

Oct. 19, 2016

Sup kernelnewbies http://salesforce.nagabendu.com/assets/uploads/Louis.php?coast=1ngbn9629nez… Anders

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Fw: TPS65910 Regulator Isuue
by Amit Mahadik Oct. 18, 2016

Oct. 18, 2016

Hi, I am working on integrating TPS695190 regulator code into kernel version 4.4.16. The regulator powers MMC card slot using Designware MMC controller. I have declared the necessary code in my board.c file. The MMC card slot is powered by ldo8 supply declared as -----------------------------------------------------------------------------Code--------------------------------------------------------------------------------- static struct regulator_consumer_supply opv5xc_ldo8_supply[] = { REGULATOR_SUPPLY("sd_vdd", NULL), }; static struct regulator_init_data opv5xc_ldo8 = { .constraints = { .min_uV = 1000000, .max_uV = 3300000, .valid_ops_mask = (REGULATOR_CHANGE_VOLTAGE | REGULATOR_CHANGE_STATUS), .boot_on = 1, }, .num_consumer_supplies = ARRAY_SIZE(opv5xc_ldo8_supply), .consumer_supplies = opv5xc_ldo8_supply, }; static struct tps65910_board tps65910_pdata = { .tps65910_pmic_init_data[TPS65911_REG_LDO8] = &opv5xc_ldo8, }; static struct i2c_board_info __initdata opv5xc_i2c1_devs[] = { { I2C_BOARD_INFO ("tps65911", TPS65910_I2C_ID1), .platform_data = &tps65910_pdata, }, }; ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- When I call regulator_get struct regulator *sd_vdd = regulator_get(NULL, "sd_vdd"); function from the Designware MMC driver code function the kernel panics.I have attached the log file for reference. Can somebody please let me know what I am doing wrong here? Regards,Amit.

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kernel loglevel
by Wenda Ni Oct. 18, 2016

Oct. 18, 2016

Dear all, I am working on a kernel module that incorporate both pr_debug and pr_warn. I would like to see pr_debug messages from dmesg. What I followed is to specify kernel parameter by saying "loglevel=7". This can be seen confirmed from /proc/cmdline. But still, I donot get pr_debug level messages either from dmesg or from /var/log/messages. I also tried echo 7 > /proc/sys/kernel/printk. It does not return what I expect, either. Let me know what I am missing. Thank you very much in advance. Cheers, Wenda Ni, Ph.D.

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