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Unable to resume after suspend/wfi state
by Amit Mahadik Nov. 10, 2016

Nov. 10, 2016

Hi, I am trying to understand the Linux Power management Unit framework. I have an ARM Cortex-A9x4 board. When I enable pm_test or pass initcall_debug parameter through U-boot via bootargs the system goes into (wfi/suspend state) and resumes properly.However, the issue is when I disable pm_test and initcall_debug and put my system into WFI/SUSPEND state , it does not resume even if the registered wakeup IRQ is generated. I am using linux kernel source revision 4.4.16. Can somebody please help me regarding this issue? Regards,Amit.

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Cannot boot to compiled kernel
by Daniel Bokser Nov. 10, 2016

Nov. 10, 2016

Hi Everyone, I know this is probably the newbiest of questions, but I am trying to compile and boot off of the kernel. I am running Arch Linux and I am following this guide: https://wiki.archlinux.org/index.php/Kernels/Traditional_compilation Despite using "linux480" below (I tried this a few weeks ago), the kernel version I am using is Linux 4.9.0-rc3 "Psychotic Stoned Sheep" (I love these names). I use systemd-boot as a boot loader. 1) Pulled down kernel from git 2) Ran make localmodconfig 3) Ran make menuconfig and changed the local version to a custom string 4) Ran make 5) Ran sudo make modules_install 6) Ran sudo cp arch/x86_64/bzImage /boot/vmlinuz-linux480 7) Added /etc/mkinitcpio.d/linux480.preset, which is similar to linux.preset except with linux480 names 8) Ran mkinitcpio -p linux480 9) Ran sudo cp System.map /boot/System.map-linux480 10) Added entry file to /boot/entries called linux480 and used the current entry as a template 11) Rebooted and selected linux480 Now I am thrown into the recovery shell with an 'Unable to find root device /dev/sdc2' (my SSD). The real strange thing is that the (PS/2) keyboard doesn't work, so I can't even run commands. Tried also USB keyboard to no avail. I also have a bunch of "Unknown symbol" errors from scsi_mod which fill most of the screen. I'm thinking the RAM disk is bad, but not sure. No amount of Google-fu was able to help me out with this one. Any help would be appreciated. Thank you! -Daniel

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Re: When I clone the kernel source, I encounter a fatal error.
by Hao Lee Nov. 9, 2016

Nov. 9, 2016

I have tried packedGitWindowSize, packedGitLimit, windowMemory, packSizeLimit and other options, but it seems that cloning the whole history still need a lot of memory and Git will be killed by OOM. Finally, I find that I can clone the latest commit of all branches with 'git clone --depth=1 --no-single-branch'. Although my local repository doesn't have any history commits, I can still track remote updates. I hope my approach can help someone who want to have a lightweight repository. Thanks for everyone's help ! Thanks, Hao Lee.

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When I clone the kernel source, I encounter a fatal error.
by Hao Lee Nov. 8, 2016

Nov. 8, 2016

Hi, I used to run 'git clone --depth=1' to get kernel source, because this way is very lightweight. But today, I want to clone the whole git repository with 'git clone git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git' Then, I encounter a problem. The output is : Cloning into 'linux-stable'... remote: Counting objects: 5531619, done. remote: Compressing objects: 100% (492978/492978), done. error: index-pack died of signal 9531619), 777.26 MiB | 19.22 MiB/s fatal: index-pack failed I do this on my VPS which has 768M memory. Is it because the memory is not enough? If so, is it possible to limit the memory usage of Git? Thanks! Hao Lee

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Understanding Platform devices and platform drivers.
by Madhu K Nov. 7, 2016

Nov. 7, 2016

Hi All, I am trying to understand the concept of platform device and platform driver, my very basic question is that, the devices and data which is present in device tree represents platform devices and platform data? Regards, Madhu

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The sequence of the built in kernel module be probed
by Hao Zhang Nov. 7, 2016

Nov. 7, 2016

hi, what's the sequence of the built in kernel module be probed? and how to change it ?

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PCI drivers and interrupts
by Kenneth Adam Miller Nov. 4, 2016

Nov. 4, 2016

Hello, I'm trying to author a driver that communicates over shared memory within the kernel land between concurrent userland processes. I'm using this as a base: https://github.com/henning-schild/ivshmem-guest-code/blob/master/kernel_mod… I've been able to build it and to insmod it into a linux that I have built and started running in qemu. I need a way to send an interrupt, as per the documentation mentions in the device_spec and in the guide. But I'm looking in the uio_ivshmem driver and I don't see functionality that corresponds to sending an interrupt at all. This functionality is supposed to be demonstrated in https://github.com/henning-schild/ivshmem-guest-code/tree/master/tests/Inte…, but this is problematic because it seems to indicate that one of the ioctls corresponds to an interrupt. Unless there's something I'm missing, I think that the stub pci driver implementation that this particular demo filled out implements some kind of interrupt, or else it's actually implemented with one of the function calls on line 28 or 43. But those each seem to correspond to interrupt handlers for receiving from other QEMU instances, with no sign of how they are *sent*. I need to write a function in the context of the driver that can be compiled in the same code, meaning editing uio_ivshmem.c and yielding some function interface like send_interrupt(int index), where index corresponds to the BAR against which the driver registers irq handlers anyway. How can I send interrupts from the kernel land using a particular BAR entry?

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zap_pid_ns_processes(struct pid_namespace)
by David Rodic Nov. 4, 2016

Nov. 4, 2016

Hi guys, I am reading "Linux Kernel Development". I came across the function call zap_pid_ns_processes(struct pid_namespace) inside the find_new_reaper function. Can someone tell me what this function does and why it is being called inside the find_new_reaper function? Thanks, David

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PMU suspend/resume
by Amit Mahadik Nov. 2, 2016

Nov. 2, 2016

Hi, I am trying to understand the Linux Power management Unit framework. I have an ARM Cortex-A9x4 board. When I enable pm_test or pass initcall_debug parameter through U-boot via bootargs the system goes into (wfi/suspend state) and resumes properly.However, the issue is when I disable pm_test and initcall_debug and put my system into WFI/SUSPEND state , it does not resume even if the registered wakeup IRQ is generated. I am using linux kernel source revision 4.4.16. Can somebody please help me regarding this issue? Regards,Amit.

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ip rule suppress_prefixlength
by Matthias Peter Walther Nov. 1, 2016

Nov. 1, 2016

Dear Linux-friends, I asked this question before on the netdev-Mailinglist, but never got an answer (Link: https://www.mail-archive.com/netdev@vger.kernel.org/msg133574.html) Maybe someone here can help me. I have a configuration like this: root@des1 ~ # ip rule 0: from all lookup local 32765: from all iif lo lookup ffnet suppress_prefixlength 0 32766: from all lookup main 32767: from all lookup default (ffnet is table 42) root@des1 ~ # ip r s default via 5.9.86.151 dev eth0 5.9.86.151 dev eth0 proto kernel scope link src 5.9.86.144 root@des1 ~ # ip r s t 42 blackhole default I have the default routing table, and a routing table number 42. I could use an ip rule filtering by destination ip, but I wanted to try suppress_prefixlength. Let's say I want to ping 8.8.8.8. What I expect is, that the package is put into routing table 42 by the ip rule 32765. As there is no more specific route for 8.8.8.8 than the default route in table 42, I expect the suppress_prefixlength 0 option to put it back to the default routing table and then to be send out through eth0. Instead this configuration takes the whole machine offline: root@des1 ~ # ping 8.8.8.8 connect: Invalid argument When I delete the ip rule 32765 containing the suppress_prefixlength, the machine is back online. Do I not understand the suppress_prefixlength-feature correctly or is this a bug? I tested with Kernel 4.7 and 4.6, both show the same behaviour as described above. Thanks for any replies in advance. Regards, Matthias

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