March 2011 - kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

Debug kernel panic with gdb?
by Arvid Brodin March 25, 2011

March 25, 2011

Hi, I'm trying to debug a kernel panic (something like this): Unable to handle kernel NULL pointer dereference at virtual address 00000014 ptbr = 93959000 pgd = 93a0a000 Oops: Kernel access of bad area, sig: 11 [#1] FRAME_POINTER chip: 0x01f:0x1e82 rev 2 Modules linked in: ftdi_sio usbserial PC is at isp1760_irq+0xda/0x7f0 LR is at isp1760_irq+0x492/0x7f0 pc : [<901408be>] lr : [<90140c76>] Not tainted sp : 93aa399c r12: fffffffe r11: 00000000 r10: 00000000 r9 : fffffffe r8 : 00000000 r7 : 93aa3a08 r6 : 93406400 r5 : 00820004 r4 : 00000003 r3 : 00000008 r2 : 00000002 r1 : fffffffd r0 : 93837000 Call trace: [<90134abc>] usb_hcd_irq+0x50/0x54 [<900383da>] handle_IRQ_event+0x1e/0x40 [<90039098>] handle_level_irq+0x78/0x8c ... This is on an AVR32 platform, and I'm building the kernel myself (cross compiling). The image is then converted to a uImage before being loaded to the target. Is there a way to get the following to work in this context? $ gdb arch/avr32/boot/images/vmlinux.elf ... Reading symbols from /home/.../linux-2.6.37/arch/avr32/boot/images/vmlinux.elf...done. (gdb) list *isp1760_irq+0xda 0x9017ac36 is in isp1760_irq (include/linux/spinlock.h:285). 280 raw_spin_lock_init(&(_lock)->rlock); \ 281 } while (0) 282 283 static inline void spin_lock(spinlock_t *lock) 284 { 285 raw_spin_lock(&lock->rlock); 286 } 287 288 static inline void spin_lock_bh(spinlock_t *lock) 289 { The problem is that the line reported is totally wrong (this being very unhelpful and confusing indeed - it tool me awhile to realise this!). I've also tried to use gdb from the avr32 toolchain with the same result. Is there a way to get this to work? Thanks, Arvid Brodin Enea Services Stockholm AB

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console debugging without a serial line
by julie Sullivan March 24, 2011

March 24, 2011

Hi list On linux-kernel today there were a couple of interesting tips for debugging the kernel from a console in the absence of a serial port. I thought this might be useful/interesting to someone here (it was to me) so here's the link: https://lkml.org/lkml/2011/3/23/1 Andi Kleen mentions the following: >There is also USB debugport, but you need a quite expensive cable >(~$100) for it. Usually it only works on one of the USB ports. Googling for 'USB Debugport' found this, which also might be useful: http://www.coreboot.org/EHCI_Debug_Port#AMIDebug_RX Does anyone (who might also be interested in reading this article) know if the 'Ajays NET20DC USB Debug Device' mentioned in this article might be the 'quite expensive cable' mentioned by Andi? (I saw one of these listed for $89.) Apart from generally coming in handy, I have a netbook I'm thinking of sacrificing as a kernel testbox in the future which I'm sure doesn't have a serial port... (yep, I think that's a really great excuse for buying yet another new funky device :-) ) Cheers Julie

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maranello for staging ?
by Jim Cromie March 24, 2011

March 24, 2011

we have, at http://www.cs.umd.edu/projects/maranello/ Abstract In this project, we design, implement, and evaluate Maranello, a novel partial packet recovery mechanism for 802.11. In Maranello, the receiver computes checksums over blocks in corrupt packets and bundles these checksums into a negative acknowledgment sent when the sender expects to receive an acknowledgment. The sender then retransmits only those blocks for which the checksum is incorrect, and repeats this partial retransmission until it receives an acknowledgment. Successful transmissions are not burdened by additional bits and the receiver needs not infer which bits were corrupted. We implemented Maranello using OpenFWWF (open source firmware for Broadcom wireless cards) and deployed it in a small testbed. We compare Maranello to alternative recovery protocols using a trace-driven simulation and to 802.11 using a live implementation under various channel conditions. To our knowledge, Maranello is the first partial packet recovery design to be implemented in commonly-available firmware. This is cool stuff. Im probably jumping the gun a bit, but well, its cool, and I have a wrt54g router to eventually try it on. I dont however have both sides of a wifi connection, so I wont be able to actually test it. Ive taken the patches on the site, applied them to 2.6.29-rc2, and started working them a bit to make them suitable for inclusion. Naturally I have questions: I started with their patches verbatim, as this preserves their provenance, and limits my chances of screwing up and making an unmaintainable mess out of them. Does staging tree value the preservation of provenance ? Or does it want all patches in the set to be "proper" (at minimum passing checkpatch). If so, I should keep the style fixups separate, instead of folding them back in to make each patch (including the original maranello patches) pass the objective criteria. How do I balance these competing interests ? Also, I figure Im serving several different purposes (or audiences) here; - inclusion (2.6.4x ?) - maranello team (success would be them adopting this rework in progress) - OpenWRT development - serious pool of hackers and devices to test upon (10.03.1-rc4 is using 2.6.32.25 currently, I dont know future kernel plans) I have a github repo: https://github.com/jimc/linux-2.6 and have pushed the following to mx0a branch. jimc@chumly:~/projects/lx/linux-2.6$ git log --oneline 4bb61c8 maranello.h defines maranello_stats, use it. 856f571 add spaces after C keywords e1251f1 fixup C99 comments e663495 cleanfile drivers/net/wireless/b43/phy_common.h too 2c67a78 run cleanfile, fix whitespace problems added by original patches 07bc126 extract maranello common parts 1 04f010b patch -p0 < maranello_released_kernelpatches/b43.patch 59f4336 patch -p0 < maranello_released_kernelpatches/include.patch 6cc5022 patch -p0 < maranello_released_kernelpatches/mac80211.patch 1de9e8e Linux 2.6.29-rc2 I merged this branch up with 2.6.32, and found I had to do ~6 merge fixups. I tried merge --squash, in effort to catch the changes to a separate commit; but that puts the commit on the 'wrong' branch - and it ISTM that it doesnt catch just the conflict resolution diffs, but rather the sum of all the diffs in the other branch. I was hoping to do a series of merge --squashes, and adapt the branch by slowly working up the various commits of master; effectively climbing the ladder. Is this a sane, straightforward strategy ? I figured Id select merge-points with this: 'git log --oneline drivers/net/wireless/b43' Im not quite sure how to proceed with this, Ive refrained from sending to netdev(a)kernel.org, I guess Id like advice and feedback 1st. thanks

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Regarding hugetlbfs
by solmac john March 24, 2011

March 24, 2011

Hi All, I am having the following query regarding Huge pages and hugetlbfs. 1-> How Hugetlbfs is dependent on hardware ? 2-> Huge pages which is architecture dependent and ARM arm architecture supports Tiny, small and large pages will it support hugetlbfs if not then why ? can some one guide me thanks in advance Thanks John

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ACPI errors during bootup
by sri March 24, 2011

March 24, 2011

Hi, Am trying to build SMP kernel. Took kernel-2.6.18-194.src.rpm, extracted, rpmbuilded with SMP option. Successfully compile the new kernel and when using that kernel to boot up, following errors were shown up(highlighted in bold & red color): My kernel config file has ACPI and PCI configs enabled. Any pointers to what caused the problem are appreciated. *************************************************************************************************************** BIOS-e820: 0000000000010000 - 000000000009e000 (usable) BIOS-e820: 000000000009e000 - 00000000000a0000 (reserved) BIOS-e820: 00000000000e0000 - 0000000000100000 (reserved) BIOS-e820: 0000000000100000 - 000000001fee9000 (usable) BIOS-e820: 000000001fee9000 - 0000000020000000 (reserved) BIOS-e820: 00000000fff00000 - 0000000100000000 (reserved) 0MB HIGHMEM available. 510MB LOWMEM available. Memory for crash kernel (0x0 to 0x0) notwithin permissible range disabling kdump Using x86 segment limits to approximate NX protection DMI not present or invalid. Using APIC driver default ACPI: Unable to locate RSDP Allocating PCI resources starting at 30000000 (gap: 20000000:dff00000) Detected 1000.103 MHz processor. Built 1 zonelists. Total pages: 130793 Kernel command line: root=/dev/ram ramdisk_size=200000 ramdisk_start=0x6000000 c onsole=ttyS0,9600n8 plat=bryce reboot=warm n Local APIC disabled by BIOS -- you can enable it with "lapic" Enabling fast FPU save and restore... done. Enabling unmasked SIMD FPU exception support... done. Initializing CPU#0 CPU 0 irqstacks, hard=c076f000 soft=c074f000 PID hash table entries: 2048 (order: 11, 8192 bytes) Console: colour dummy device 80x25 Dentry cache hash table entries: 65536 (order: 6, 262144 bytes) Inode-cache hash table entries: 32768 (order: 5, 131072 bytes) Memory: 503320k/523172k available (2189k kernel code, 19224k reserved, 920k data , 232k init, 0k highmem) Checking if this processor honours the WP bit even in supervisor mode... Ok. Calibrating delay loop (skipped), value calculated using timer frequency.. 2000. 20 BogoMIPS (lpj=1000103) Security Framework v1.0.0 initialized SELinux: Initializing. selinux_register_security: Registering secondary module capability Capability LSM initialized as secondary Mount-cache hash table entries: 512 CPU: L1 I cache: 32K, L1 D cache: 32K CPU: L2 cache: 512K Intel machine check architecture supported. Intel machine check reporting enabled on CPU#0. Checking 'hlt' instruction... OK. SMP alternatives: switching to UP code Freeing SMP alternatives: 14k freed CPU0: Intel(R) Celeron(R) M processor 1.00GHz stepping 08 SMP motherboard not detected. Local APIC not detected. Using dummy APIC emulation. Brought up 1 CPUs *checking if image is initramfs... it is Freeing initrd memory: 10554k freed NET: Registered protocol family 16 PCI: PCI BIOS revision 2.10 entry at 0xff67f, last bus=4 PCI: Using configuration type 1 Setting up standard PCI resources ACPI: Interpreter disabled. Linux Plug and Play Support v0.97 (c) Adam Belay pnp: PnP ACPI: disabled usbcore: registered new driver usbfs usbcore: registered new driver hub PCI: Probing PCI hardware ACPI Error (tbxfroot-0645): No valid RSDP was found [20060707] ACPI Exception (tbxfroot-0400): AE_NOT_FOUND, RSDP structure not found - Flags=8 [20060707] ACPI: System description tables not found ACPI Error (tbxfroot-0645): No valid RSDP was found [20060707] ACPI Exception (tbxfroot-0400): AE_NOT_FOUND, RSDP structure not found - Flags=8 [20060707] ACPI: System description tables not found ACPI Error (tbxfroot-0645): No valid RSDP was found [20060707] ACPI Exception (tbxfroot-0400): AE_NOT_FOUND, RSDP structure not found - Flags=8 [20060707] ACPI: System description tables not found ACPI Error (tbxfroot-0645): No valid RSDP was found [20060707] ACPI Exception (tbxfroot-0400): AE_NOT_FOUND, RSDP structure not found - Flags=8 [20060707] ACPI: System description tables not found ACPI Error (tbxfroot-0645): No valid RSDP was found [20060707] ACPI Exception (tbxfroot-0400): AE_NOT_FOUND, RSDP structure not found - Flags=8 [20060707] ACPI: System description tables not found ACPI Error (tbxfroot-0645): No valid RSDP was found [20060707] ACPI Exception (tbxfroot-0400): AE_NOT_FOUND, RSDP structure not found - Flags=8 [20060707] ACPI: System description tables not found ACPI Error (tbxfroot-0645): No valid RSDP was found [20060707] ACPI Exception (tbxfroot-0400): AE_NOT_FOUND, RSDP structure not found - Flags=8 [20060707] ACPI: System description tables not found ACPI Error (tbxfroot-0645): No valid RSDP was found [20060707] ACPI Exception (tbxfroot-0400): AE_NOT_FOUND, RSDP structure not found - Flags=8 [20060707] ACPI: System description tables not found ACPI Error (tbxfroot-0645): No valid RSDP was found [20060707] ACPI Exception (tbxfroot-0400): AE_NOT_FOUND, RSDP structure not found - Flags=8 [20060707] ACPI: System description tables not found ACPI Error (tbxfroot-0645): No valid RSDP was found [20060707] ACPI Exception (tbxfroot-0400): AE_NOT_FOUND, RSDP structure not found - Flags=8 [20060707] ACPI: System description tables not found ACPI Error (tbxfroot-0645): No valid RSDP was found [20060707] ACPI Exception (tbxfroot-0400): AE_NOT_FOUND, RSDP structure not found - Flags=8 [20060707] ACPI: System description tables not found ACPI Error (tbxfroot-0645): No valid RSDP was found [20060707] ACPI Exception (tbxfroot-0400): AE_NOT_FOUND, RSDP structure not found - Flags=8 [20060707] ACPI: System description tables not found PCI quirk: region 1000-107f claimed by ICH4 ACPI/GPIO/TCO PCI quirk: region 0500-053f claimed by ICH4 GPIO ACPI Error (tbxfroot-0645): No valid RSDP was found [20060707] ACPI Exception (tbxfroot-0400): AE_NOT_FOUND, RSDP structure not found - Flags=8 [20060707] ACPI: System description tables not found PCI: Ignoring BAR0-3 of IDE controller 0000:00:1f.2 ACPI Error (tbxfroot-0645): No valid RSDP was found [20060707] ACPI Exception (tbxfroot-0400): AE_NOT_FOUND, RSDP structure not found - Flags=8 [20060707] ACPI: System description tables not found ACPI Error (tbxfroot-0645): No valid RSDP was found [20060707] ACPI Exception (tbxfroot-0400): AE_NOT_FOUND, RSDP structure not found - Flags=8 [20060707] ACPI: System description tables not found ACPI Error (tbxfroot-0645): No valid RSDP was found [20060707] ACPI Exception (tbxfroot-0400): AE_NOT_FOUND, RSDP structure not found - Flags=8 [20060707] ACPI: System description tables not found ACPI Error (tbxfroot-0645): No valid RSDP was found [20060707] ACPI Exception (tbxfroot-0400): AE_NOT_FOUND, RSDP structure not found - Flags=8 [20060707] ACPI: System description tables not found* PCI: Transparent bridge - 0000:00:1e.0 NetLabel: Initializing NetLabel: domain hash size = 128 NetLabel: protocols = UNLABELED CIPSOv4 NetLabel: unlabeled traffic allowed by default PCI: Bridge: 0000:00:02.0 IO window: c000-0000 MEM window: c0100000-00000000 PREFETCH window: disabled. PCI: Bridge: 0000:00:03.0 IO window: disabled. MEM window: disabled. PREFETCH window: disabled. PCI: Bridge: 0000:00:1c.0 IO window: disabled. MEM window: disabled. PREFETCH window: disabled. PCI: Bridge: 0000:00:1e.0 IO window: disabled. MEM window: disabled. PREFETCH window: disabled. PCI: No IRQ known for interrupt pin A of device 0000:00:02.0. Please try using p ci=biosirq. PCI: No IRQ known for interrupt pin A of device 0000:00:03.0. Please try using p ci=biosirq. NET: Registered protocol family 2 IP route cache hash table entries: 4096 (order: 2, 16384 bytes) TCP established hash table entries: 16384 (order: 5, 131072 bytes) TCP bind hash table entries: 8192 (order: 4, 65536 bytes) TCP: Hash tables configured (established 16384 bind 8192) TCP reno registered apm: BIOS not found. audit: initializing netlink socket (disabled) type=2000 audit(1300527457.278:1): initialized Total HugeTLB memory allocated, 0 VFS: Disk quotas dquot_6.5.1 Dquot-cache hash table entries: 1024 (order 0, 4096 bytes) Initializing Cryptographic API alg: No test for crc32c (crc32c-generic) ksign: Installing public key data Loading keyring io scheduler noop registered io scheduler anticipatory registered io scheduler deadline registered io scheduler cfq registered (default) pcieport-driver 0000:00:02.0: device [8086:3595] has invalid IRQ; check vendor B IOS pcieport-driver 0000:00:03.0: device [8086:3596] has invalid IRQ; check vendor B IOS pci_hotplug: PCI Hot Plug PCI Core version: 0.5 ************************************************************************************************************************** -- -- Krishna Mohan B

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Re: ACPI errors during bootup
by Mulyadi Santosa March 24, 2011

March 24, 2011

Hi... On Thu, Mar 24, 2011 at 10:14, sri <bskmohan(a)gmail.com> wrote: > > Please see the attached config diff txt file. Please keep "kernelnewbies" intact.... from what I see, you forgot to enable CONFIG_ACPI. See this line? -CONFIG_ACPI=y I might be mistaken, so pls check your current kernel config, not the default one from the RPM (you did use the one from kernel RPM as the basis, do you?) -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com

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<Query> Regarding static and shared (dynamic) libraries linking
by Leelakrishna A March 23, 2011

March 23, 2011

Hi All, I have few doubts regarding static and shared (dynamic) libraries linking. Can anybody please clarify it. There are two kinds of libraries - static libary(.a file) and shared library (.so file). Also there are two types of library linkages static linkage and dynamic linkage. So Static library can be linked to an executable in either ways (Statically and dynamically). in the same way shared libraries can be linked to executable in both the ways (Statically and dynamically). Here my doubt is what is the use if we statically linked the shared library to the executable binary (by this way the shared library is part of the executable) and what is the point in calling it as shared libary if it can be linked statically to the executable file. If we linked the shared library to the executable file using dynamic linkage, executable file will pick the library at run time. Here my doubt is to pick up the library at run time who will load the library into the memory and how will the executable know about the address of the function in the library to invoke the function. Thanks in advance, Leela krishna.

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Debugging Infinite Loop
by Dev Null March 22, 2011

March 22, 2011

Hi, I have an infinite loop in my huge application/kernel module i.e. either in kernel or application that boost up CPU utilization to 100%. I have an application that reads multicast UDP packet, process it and send it to the peripheral device on PCI interface. I need to know the best approach or tool to debug the infinite loop. Thanks, Dev Null

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Re: hi one doubt
by Mulyadi Santosa March 22, 2011

March 22, 2011

On Tue, Mar 22, 2011 at 23:57, pradeepkumar soman <pradeep2481(a)gmail.com> wrote: > Hello, > I have a doubt related to a network relay device. Looking at my skill level, I am probably not a right person to answer this. So pardon me if I cc: this e-mail to the kernelnewbies list... hopefully it gets better answer here... > I am having a relay device which will clone the skb and route the cloned > packet to another interface (it is doing packet interception) during the > packet transmission. I am not really sure on what "a relay device" means here.... do you mean something like dummy device (kinda "lo") and anything send to it will be "copied" to another ethernet device like what we do with "iptables" using "redirect" target? > But I am getting the error "Dead loop on netdevice relay" frequently on high > data transfer. "Frequently" or always? what's the percentage? >This error is coming from net/sched/sched_generic.c, whenever > the > hard_xmit function is recursive. But the hard_xmit function is called with > bh and kernel preemption disabled. So what is the reason for this scenario > to occur? Let's step back a bit: how do you send the data anyway? it might be due to send it using hard_xmit or anything like that...then intercept it right after it is received by the "device" and send to another one.... so you send, intercept, send again likely in the same context or code path.... got what I meant? you probably just need to put the data in the right skb queue and trigger the net_tx something ( forgot the name), thus it each are done by different workqueue context.... -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com

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None
by nijil yes March 22, 2011

March 22, 2011

Hi, could anyone mention what are the projects available for beginners to do in gsoc this time from kernel newbies.I am comfortable with c/c++.I would be glad if someone could suggest a few Regards, Nijil

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