July 2017 - kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

how to get consistent value of "nf_conntrack_htable_size" and "nf_conntrack_hash" in a kernel module ?
by Shiyao Ma July 7, 2017

July 7, 2017

Hi, I want to foreach all the `struct nf_conn's in my out-of-tree kernel module. My plan is to get the `nf_conntrack_htable_size' and `nf_conntrack_hash', then do some read on the hash table. However, the symbol `nf_conntrack_generation' is not exported, so I cannot do things like this: struct hlist_nulls_head *hptr; unsigned int sequence, hsz; do { sequence = read_seqcount_begin(&nf_conntrack_generation); hsz = nf_conntrack_htable_size; hptr = nf_conntrack_hash; } while (read_seqcount_retry(&nf_conntrack_generation, sequence)); How to get a consistent value of `nf_conntrack_htable_size' and `nf_conntrack_hash' ? Thanks.

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Can I use the same .config file to compile 32-bit and 64-bit kernel?
by Hao Lee July 7, 2017

July 7, 2017

Hi, I'm currently configuring a custom kernel on Fedora x86_64. The first option on the configuration menu is "64-bit kernel" which I think is the only option controlling the architecture of kernel. Copying this .config file to a 32-bit system directly and turning off this option, can I compile a 32-bit kernel which doesn't have any hidden problems? If this way is feasible, I think the only difference between these two kernels is architecture. Regards, Hao Lee

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Re: Eudyptula Challenge scripts not responding?
by Laurence Rochfort July 6, 2017

July 6, 2017

Thanks all. Yeah, I understand a judgement on a submission could take a while, but I wasn't getting an auto-response either. Looks like it was a mail routing issue on my side and I also got the subject format wrong. On Thu, 6 Jul 2017, 17:24 David Wittman, <dwittman(a)gmail.com> wrote: > That said, the autoresponder should reply pretty quickly after your > submission. > > On Thu, Jul 6, 2017 at 9:30 AM, Alexander Kapshuk < > alexander.kapshuk(a)gmail.com> wrote: > >> On Thu, Jul 6, 2017 at 4:04 PM, Laurence Rochfort >> <laurence.rochfort(a)gmail.com> wrote: >> > Hi all, >> > >> > The Eudyptula Challenge scripts seem to not be responding these past few >> > days. >> > >> > if anybody here is involved behind the scenes, would you please take a >> look? >> > >> > Cheers, >> > Laurence. >> > >> > _______________________________________________ >> > Kernelnewbies mailing list >> > Kernelnewbies(a)kernelnewbies.org >> > https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >> > >> >> The response times vary between hearing from them the same day to up >> to a few weeks. >> >> They will get back to you eventually. >> >> _______________________________________________ >> Kernelnewbies mailing list >> Kernelnewbies(a)kernelnewbies.org >> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >> > >

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Eudyptula Challenge scripts not responding?
by Laurence Rochfort July 6, 2017

July 6, 2017

Hi all, The Eudyptula Challenge scripts seem to not be responding these past few days. if anybody here is involved behind the scenes, would you please take a look? Cheers, Laurence.

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How to alloc_pages from a given physical memory?
by kipade July 6, 2017

July 6, 2017

Here I want to allocate a block of shared memory from a given physical address, such as 0x90000000, 6M. However, alloc_pages can't fit this point. I had reserved enugh pages via cmem, there also have enough continous pages for such allocation anywhere else. What should I do?

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Kernel header inclusion practice
by Shiyao MA July 5, 2017

July 5, 2017

Hi, How do you include the kernel headers? For example, Currently I have the headers: #include <linux/module.h> #include <linux/kthread.h> #include <linux/delay.h> And now I wanna use the `struct workqueue_struct'. It turns out I don't have to include the "linux/workqueue.h". So it must have already been included by the three headers above. My question is: What's the practice of including headers? Should I specifically include "linux/workqueue.h" ? Another question is particular to the above three headers: does any of them guarantee to include the "linux/queue.h"? If there is any documentation about the API of the headers (e.g., what they include), that will be great. Best

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building af_packet as a kernel module
by Kevin Wilson July 3, 2017

July 3, 2017

Hello, I have tried to set CONFIG_PACKET=m in kernel 4.11 and rebuilt the kernel and rebooted. I am using Ubuntu 16.04. After reboot, the af_packet.ko kernel module is loaded: lsmod shows: af_packet 45056 2 But I cannot remove it: rmmod af_packet rmmod: ERROR: Module af_packet is in use I want to be able to rmmod it, for adding debug printing, etc. How can I find which applications uses it ? (So I will be able to stop them, rmmod af_packet, and then insmod it again)? Regards, Kevin

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Qemu+busybox for kernel development
by Alexander Kapshuk July 2, 2017

July 2, 2017

I am trying to setup a build environment where I can run the kernel and see how the changes I have made to the kernel source work. My understanding, based on googling, is that it is common practice in the kernel community to use a virtualised environment for that purpose. What I have done so far is create a ramfs that is built into the kernel, as described here [1] and here [2]. [1] https://landley.net/writing/rootfs-howto.html [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/Do… a). I have generated a minimal initramfs_list file: scripts/gen_initramfs_list.sh -d >usr/initramfs_list Which looks like this: # This is a very simple, default initramfs dir /dev 0755 0 0 nod /dev/console 0600 0 0 c 5 1 dir /root 0700 0 0 # file /kinit usr/kinit/kinit 0755 0 0 # slink /init kinit 0755 0 0 slink /bin/sh busybox 777 0 0 file /init /bin/busybox 755 0 0 b). Set CONFIG_INITRAMFS_SOURCE: CONFIG_INITRAMFS_SOURCE="/home/sasha/linux/usr/initramfs_list" c). And had the kernel generate the initramfs image: make ... GEN usr/initramfs_data.cpio.gz CHK include/generated/compile.h AS usr/initramfs_data.o LD usr/built-in.o ... When I run the kernel in qemu I get an error message which complains about /etc/init.d/rcS missing. The posts online seem to suggest that this has got to do with the busybox configuration. So far, I have not been able to get my head around this problem. Any points or suggestions would be much appreciated. Alexander Kapshuk.

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