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make headers_install for out-of-tree modules
by Daniel. Oct. 8, 2015

Oct. 8, 2015

Hi all, I'm trying to install headers from out-of-tree module. I've writed this[1] Makefile. I have Kbuild files with header-y tokens poiting for propper folders and files. When I run "make headers_install" I got this[2] error message, [1] http://pastebin.com/9f3kYT8k [2] http://pastebin.com/yfi69nUi Any idea? Best regards, -- "Do or do not. There is no try" Yoda Master

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Without "make modules" command, we can also execute "make modules_install" command?
by Nan Xiao Oct. 8, 2015

Oct. 8, 2015

Hi all, >From KernelBuild <http://kernelnewbies.org/KernelBuild> post, I don't see "make modules" command. This article only executes "make" command before "sudo make modules_install install". So I am a little confused, is "make modules" optional in building kernel? No "make modules" command, we can also execute "make modules_install" command? Thanks very much in advance! Best Regards Nan Xiao

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Eudyptula challenge task 8 no reply so far
by Vinicius Tinti Oct. 7, 2015

Oct. 7, 2015

Hi, Is anyone stuck on task 8 too? I have sent again my files and notice that it is still processing September 5th. Could someone check? Regards, Vinicius -- Simplicity is the ultimate sophistication

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UIO Devices and user processes
by Kenneth Adam Miller Oct. 7, 2015

Oct. 7, 2015

So, I'm reading about UIO devices and user processes for mapping memory into userland, and basically I have just a couple questions: What happens when a userland processes has allocated some resource from a driver that is facilitating UIO, but then subsequently crashes? I'd like to know that the driver can (or how you would enable such) recover the resources so that the next user process can acquire them, instead of them being lost. We have a specific region of memory that we'd like to allocate to a process, and we'd like effectively all new and delete or malloc and free operations to be done against this target area. We'd like to not have to use placement new in C++-just transparently for the requesting user process to receive chunks from a specific real region of memory. Thanks in advance.

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How to get user level stack trace of an application from system crash
by Shailendra Rana Oct. 7, 2015

Oct. 7, 2015

Hi, I have an application which traps file events using fanotify, process these events and gives a verdict to fanotify whether access to a file is allowed or not. However, in some cases the verdict does not reach fanotify and system freezes. In such a case I just have system crash to analyze the issue. My question is that is it possible to get a user level stack trace of an application using system crash ? Thanks and regards, Shailendra

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how to expand linux kernel macro in kernel source code/kernel module(outside)
by 慕冬亮 Oct. 7, 2015

Oct. 7, 2015

Recently I was learning doubly linked list in kernel, there are many macro in linux/fs.h, like list_add, list_del,list_for_each,list_entry, container_of. I know we can use "gcc -E" to expand the macro, but how do we expand the macro in kernel source code / kernel module? - mudongliang

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Re: [PATCH v3 1/4] firmware: introduce sysfs driver for QEMU's fw_cfg device
by Gabriel L. Somlo Oct. 6, 2015

Oct. 6, 2015

On Tue, Oct 06, 2015 at 10:54:42AM -0700, Andy Lutomirski wrote: > On Sat, Oct 3, 2015 at 4:28 PM, Gabriel L. Somlo <somlo(a)cmu.edu> wrote: > > From: Gabriel Somlo <somlo(a)cmu.edu> > > > > Make fw_cfg entries of type "file" available via sysfs. Entries > > are listed under /sys/firmware/qemu_fw_cfg/by_key, in folders > > named after each entry's selector key. Filename, selector value, > > and size read-only attributes are included for each entry. Also, > > a "raw" attribute allows retrieval of the full binary content of > > each entry. > > > > This patch also provides a documentation file outlining the > > guest-side "hardware" interface exposed by the QEMU fw_cfg device. > > > > What's the status of "by_name"? There's a single (presumably > incorrect) mention of it in a comment in this patch. > > I would prefer if the kernel populated by_name itself rather than > deferring that to udev, since I'd like to use this facility in virtme, > and I'd like to use fw_cfg very early on boot before I even start > udev. "by_name" is added with patch 4/4 of the series, which I kept separate due to the "To udev or not to udev" conversation from earlier. So far I haven't yet figured out just HOW I'd set it up in udev, but it works already if done in the kernel :) Thanks, --Gabriel

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Looking for easy first-timer tasks
by Sean Bollin Oct. 6, 2015

Oct. 6, 2015

Hello, I compiled the latest kernel and booted up using it on my Ubuntu distro. I'm interested in getting started doing kernel dev. Can you point me at some easy first-timer tasks? I do know C. I read the website and searched for "TODO" in driver/staging as well as ran a few of the perl style checks - but couldn't really find something as a good intro.

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Re: Help
by Mulyadi Santosa Oct. 5, 2015

Oct. 5, 2015

On Fri, Sep 25, 2015 at 10:14 PM, Prem Kumar <prem.it.kumar(a)gmail.com> wrote: > Dear Mulyadi, > > Sorry for sending direct email. I am at a deadlock pulling my hairs and > can't seem to figure out ( > http://lists.kernelnewbies.org/pipermail/kernelnewbies/2015-September/01511…) > how to reclaim the AnonHugePage allocations when only system services are > running on them. Reboot is an option but too many nodes and this happening > frequently i need to know an alternate way out. > > Any help is greatly appreciated. > Regards, > Prem > > > Dear Prem Sorry that I can not promptly answer any question these days. My quick conclusion is that, since you said you alocate huge page above, then I guess huge page has different reclaim policy, that's why it might not be released when your application terminated. maybe you forgot to explicitly release them? All in all, I appreciate you ask my help, but next time please make sure that person is inviting you for direct discussion first, so you won't be considered as impolite. -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com

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What is negative lookup in linux filesystem
by Praveen Kumar Oct. 5, 2015

Oct. 5, 2015

Hi, I am trying to understand the path-lookup in linux filesystem and was going through https://www.kernel.org/doc/Documentation/filesystems/path-lookup.txt Under 'Rename' heading, I came across the negative lookup terminology, snapshot below 'Between deleting the dentry from the old hash list, and inserting it on the new hash list, a lookup may find neither 'A' nor 'B' matching the dentry. The same rename seqlock is also used to cover this race in much the same way, by retrying a negative lookup result if a rename was in progress.' Can anyone please help understanding the negative lookup concept and how do we achieve it. Thanks in advance. Regards, ~Praveen.

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