April 2014 - kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

Re: 2.6.10 no boot
by Marcello Stanisci April 5, 2014

April 5, 2014

I have a kernel line, see "menuentry" in my grub.cfg. I don't have a initrd entry, but it should not be required 2014-04-05 16:53 GMT+02:00 Corey Sheldon <sheldon.corey(a)gmail.com>: > missing the kernel line brother see below: (edit for your setup as needed.. > > linux /vmlinuz-3.14.0-1.vanilla.mainline.knurd.1.fc20.i686 > root=/dev/mapper/luks-35c3bcf7-802e-4aba-b62f-cf17b01d54cb ro > rd.luks.uuid={snipped} > > initrd /initramfs-3.14.0-1.vanilla.mainline.knurd.1.fc20.i686.img > } > > Corey W Sheldon > Owner, 1st Class Mobile Shine > 310.909.7672 > www.facebook.com/1stclassmobileshine > > > On Sat, Apr 5, 2014 at 7:05 AM, Marcello Stanisci <stanisci.m(a)gmail.com> > wrote: >> >> Dear All, >> >> I built a linux kernel 2.6.10. When grub tries to execute it the >> system shows the message: >> >> Uncompressing Linux.. >> >> and then reboots in a very Spartan way. >> >> My suspects are that a modern bootloader tries to boot an older >> (although respectful) kernel. In facts grub does some >> preliminar, and mysterious to me, work prior to launch the kernel. >> >> In the following links you will find my .config and an excerpt of my >> grub.cfg. As an additional information, the same happens on two >> machines of mine (both having a debian wheezy), so the problem should >> not be related to hardware. >> >> .config --> http://www.polarhome.com:753/~marcello/.config >> grub.cfg --> http://www.polarhome.com:753/~marcello/grub.cfg >> >> In just one word: HELP >> >> Thanks in Advance. >> >> _______________________________________________ >> Kernelnewbies mailing list >> Kernelnewbies(a)kernelnewbies.org >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > >

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Code Style issue
by HABI S RAVI April 5, 2014

April 5, 2014

Hi, I am trying to fix a coding issue . I get the following warning when my module is checked with checkpatch.pl. How can i remove the warning. I see a lot of drivers using printk() function. $ perl ~/linux-stable/scripts/checkpatch.pl -f hello.c WARNING: Prefer netdev_dbg(netdev, ... then dev_dbg(dev, ... then pr_debug(... to printk(KERN_DEBUG ... #6: FILE: hello.c:6: + printk(KERN_DEBUG "Hello World!\n"); WARNING: Prefer netdev_dbg(netdev, ... then dev_dbg(dev, ... then pr_debug(... to printk(KERN_DEBUG ... #12: FILE: hello.c:12: + printk(KERN_DEBUG "hello module unloaded\n");

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udoo - Kernel upgrade using 3.10.17 kernel.
by Anand Moon April 5, 2014

April 5, 2014

Hi All, I am trying to update the kernel of the udoo board 3.10.17. Original kernel supported by Udoo works fine. I am able to build the kernel and load the image on the board. But is stuck at the boot loader... with following message below. I think this is bootloader problem ? If not what could be the problem for the booting of the kernel image to stop. Is it related to device tree file. Please share some pointer so that I can work on to resolve the problem. ------------------------boot message------------------------------------------- U-Boot 2013.10-rc3 (Jan 20 2014 - 13:33:34) CPU: Freescale i.MX6Q rev1.2 at 792 MHz Reset cause: POR Board: UDOO DRAM: 1 GiB MMC: FSL_SDHC: 0 *** Warning - bad CRC, using default environment No panel detected: default to LDB-WVGA Display: LDB-WVGA (800x480) In: serial Out: serial Err: serial Net: using phy at 6 FEC [PRIME] Warning: failed to set MAC address Hit any key to stop autoboot: 0 mmc0 is current device ** File not found boot.scr ** 5077712 bytes read in 419 ms (11.6 MiB/s) Booting from mmc ... ** File not found imx6q-udoo.dtb ** ## Booting kernel from Legacy Image at 12000000 ... Image Name: Linux-3.10.17-80552-gd6e35d0 Image Type: ARM Linux Kernel Image (uncompressed) Data Size: 5077648 Bytes = 4.8 MiB Load Address: 10800000 Entry Point: 10800000 Verifying Checksum ... OK Loading Kernel Image ... OK Starting kernel ... ------------------------------------------------------------------------- Please share your thought on this. -Anand Moon

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Adding a dummy system call
by Adam Fowler April 5, 2014

April 5, 2014

Hi Everyone, I am trying to learn the linux kernel via the book Linux Kernel Development 3rd edition by Robert Love, and in it he advises to use the macro _syscallX to allow access to user added syscalls not wrapped by glibc functions. In my attempt to add a system call this macro failed me and after a little man page perusal I noticed _syscallX is obselete. Is it considered a better practice to declare the asmlinkage int sys_X(..) declaration myself instead of using this obsolete macro? Or did syscall(2) replace it? And if it was replaced does anyone have a reference they could point me for adding system calls in kernel 3.10 or similar? thank you in advance!

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Special keys not working after installing newest kernel
by Riemer van der Zee April 4, 2014

April 4, 2014

Hello all, I always build a custom kernel from torvalds/linux.git as a training exercise, however since today a few of the special keys are not working. (As in/de-creasing and muting sound). I get the following errors after pressing one of these buttons: [ 47.976253] ACPI: \_SB_.ATKD: Unsupported event type 0x32 [ 50.846828] ACPI: \_SB_.ATKD: Unsupported event type 0x31 [ 51.209026] ACPI: \_SB_.ATKD: Unsupported event type 0x30 I also find the following messages worrying: [ 1.290958] ACPI Warning: SystemIO range 0x0000000000000428-0x000000000000042f conflicts with OpRegion 0x0000000000000400-0x000000000000047f (\PMIO) (20140214/utaddress-258) [ 1.290968] ACPI: If an ACPI driver is available for this device, you should use it instead of the native driver [ 1.290974] ACPI Warning: SystemIO range 0x0000000000000540-0x000000000000054f conflicts with OpRegion 0x0000000000000500-0x0000000000000549 (\SBGP) (20140214/utaddress-258) [ 1.290981] ACPI Warning: SystemIO range 0x0000000000000540-0x000000000000054f conflicts with OpRegion 0x0000000000000500-0x0000000000000563 (\GPIO) (20140214/utaddress-258) [ 1.290988] ACPI: If an ACPI driver is available for this device, you should use it instead of the native driver [ 1.290992] ACPI Warning: SystemIO range 0x0000000000000530-0x000000000000053f conflicts with OpRegion 0x0000000000000500-0x0000000000000549 (\SBGP) (20140214/utaddress-258) [ 1.290997] ACPI Warning: SystemIO range 0x0000000000000530-0x000000000000053f conflicts with OpRegion 0x0000000000000500-0x0000000000000563 (\GPIO) (20140214/utaddress-258) [ 1.291001] ACPI: If an ACPI driver is available for this device, you should use it instead of the native driver [ 1.291003] ACPI Warning: SystemIO range 0x0000000000000500-0x000000000000052f conflicts with OpRegion 0x0000000000000500-0x0000000000000549 (\SBGP) (20140214/utaddress-258) [ 1.291008] ACPI Warning: SystemIO range 0x0000000000000500-0x000000000000052f conflicts with OpRegion 0x0000000000000500-0x0000000000000563 (\GPIO) (20140214/utaddress-258) [ 1.291013] ACPI: If an ACPI driver is available for this device, you should use it instead of the native driver The laptop is an Asus n61j and a version where the keys did work is: 01d5f3b598b18a5035426c30801adf65822dbd0c my .config : http://pastebin.com/cwar1Hk7 the whole dmesg : http://pastebin.com/9jmhLskD Any pointers in how to fix this or if you require any more information I'm glad to listen/supply. Are there any recent commits to the ACPI system I can take a look at? Thank you! Riemer van der Zee

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Memory profiling tools for Linux Kernel
by Kumar Amit Mehta April 4, 2014

April 4, 2014

I was looking for some tools for memory profiling for Linux Kernel. I I wish to analyze the memory usage statistics by comparing the results (with and without the usage of Lookaside caches) by the consumer (Say a certain driver).I found some tools such as kmemcheck[1] and KEDR [2] but before I go further and explore these tools, I was wondering if somebody has already used these tools to acquire similar statistics or I should try out some other tool. [1] https://www.kernel.org/doc/Documentation/kmemcheck.txt [2] http://kedr.berlios.de/ Thanks, Kumar

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v4l2 framework in a multiple thread environment
by m silverstri April 4, 2014

April 4, 2014

Hi, I am writing a driver using v4l2 framework. I want to know does v4l2 framework make my driver thread-safe? What if multiple threads try to * open the driver * enqueue/dequeue buffer * run device_run at the same time. Do I need to add mutex myself? Of all the hooks I provide to v4l2 framework is already thread-safe? Thank you.

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Non-consistent CPU usage in IP forwarding test
by Oleg A. Arkhangelsky April 4, 2014

April 4, 2014

Hello all, We've got very strange behavior when testing IP packet forwarding performance on Sandy Bridge platform (Supermicro X9DRH with the latest BIOS). This is two socket E5-2690 CPU system. Using different PC we're generating DDoS-like traffic with rate of about 4.5 million packets per second. Traffic is receiving by two Intel 82599 NICs and forwarding using the second port of one of this NICs. All load is evenly distributed among two nodes, so each of 32 CPUs SI usage is virtually equal. Now the strangest part. Few moments after pktgen start on traffic generator PC, average CPU usage on SB system goes to 30-35%. No packet drops, no rx_missed_errors, no rx_no_dma_resources. Very nice. But SI usage starts to decreasing gradually. After about 10 seconds we see ~15% SI average among all CPUs. Still no packet drops, the same RX rate as in the beginning, RX packet count is equal to TX packet count. After some time we see that average SI usage start to go up. Peaked at initial 30-35% it goes down to 15% again. This pattern is repeated every 80 seconds. Interval is very stable. It is undoubtedly bind to the test start time, because if we start test, then interrupt it after 10 seconds and start it again we see the same 30% SI peak in a few moments. Then all timings will be the same. During the high load time we see this in "perf top -e cache-misses": 14017.00 24.9% __netdev_alloc_skb [kernel.kallsyms] 5172.00 9.2% _raw_spin_lock [kernel.kallsyms] 4722.00 8.4% build_skb [kernel.kallsyms] 3603.00 6.4% fib_table_lookup [kernel.kallsyms] During the "15% load time" top is different: 11090.00 20.9% build_skb [kernel.kallsyms] 4879.00 9.2% fib_table_lookup [kernel.kallsyms] 4756.00 9.0% ipt_do_table /lib/modules/3.12.15-BUILD-g2e94e30-dirty/kernel/net/ipv4/netfilter/ip_tables.ko 3042.00 5.7% nf_iterate [kernel.kallsyms] And __netdev_alloc_skb is at the end of list: 911.00 0.5% __netdev_alloc_skb [kernel.kallsyms] Some info from "perf stat -a sleep 2": 15% SI: 28640006291 cycles # 0.447 GHz [83.23%] 38764605205 instructions # 1.35 insns per cycle 30% SI: 56225552442 cycles # 0.877 GHz [83.23%] 39718182298 instructions # 0.71 insns per cycle CPUs never go above C1 state, all cores speed from /proc/cpuinfo is constant at 2899.942 MHz. ASPM is disabled. All non-essential userspace apps was explicitly killed for test time, there was no active cron jobs too. So we should assume no interference with userspace. Kernel version is 3.12.15 (ixgbe 3.21.2), but we have the same behavior with ancient 2.6.35 (ixgbe 3.10.16). Although on 2.6.35 we sometimes get 160-170 seconds interval and different symbols at the "perf top" output (especially local_bh_enable() which is completely blows my mind). Does anybody have some thoughts about the reasons of this kind of behavior? Sandy Bridge CPU has many uncore/offcore events, which I can sample, maybe some of them can shed some light on such behavior? Thank you! -- wbr, Oleg. "Anarchy is about taking complete responsibility for yourself." Alan Moore.

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#lsfmmsummit
by parinay April 3, 2014

April 3, 2014

http://lwn.net/Articles/LSFMM2014/ passing on. cheers -- easy is right begin right and you're easy continue easy and you're right the right way to go easy is to forget the right way and forget that the going is easy....

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/proc/slabinfo
by Pietro Paolini April 3, 2014

April 3, 2014

Hello everyone, I am experiencing a problem where the system reboot due low memory conditions, looking at the /proc/slabinfo I am able to see that a lot of memory falls under the size-1024 line with reports a high number of active objects, then in order to debug that I tried to compile with : CONFIG_DEBUG_INFO=y CONFIG_DEBUG_SLAB=y CONFIG_DEBUG_SLAB_LEAK=y Then now I am able to cat the /proc/slab_allocators leaf but that name, nor either all the size-* - are not present in that output, do you know why ? Best Regards, Pietro Paolini

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