Re: profiling functions called in interrupt context
On Tue, Sep 20, 2011 at 10:25 AM, rohan puri wrote: > > > On Tue, Sep 20, 2011 at 10:13 AM, Amit Nagal wrote: >> >> On Tue, Sep 20, 2011 at 10:05 AM, rohan puri >> wrote: >> > >> > >> > On Tue, Sep 20, 2011 at 9:44 AM, Amit Nagal >> > wrote: >> >> >> >> Hi , >> >> >> >> i want to measure time spend in a callback function called from >> >> interrupt context . >> >> since the time spend will be in us / ns , what kernel apis can i use >> >> to measure it ? >> >> >> >> also since i want to use it in interrupt context , kernel time >> >> measurement apis should not sleep . >> >> i am using embedded arm target , and tools like OProfile are not >> >> available . >> >> >> >> can i be guided which kernel time measurement apis shall i use to >> >> measure time in a interrupt callback ? >> >> >> >> Regards >> >> Amit Nagal >> > >> > For this you can make use of ftrace. >> > >> > Refer link http://www.mjmwired.net/kernel/Documentation/trace/ftrace.txt >> > >> > Regards, >> > Rohan >> > >> >> Tools like ftrace are not available to me in my embedded arm target . >> So i want to use kernel apis to deal with time measurement in >> interrupt context . >> >> Regards >> Amit Nagal > > Hi Amit, > > I think ftrace can be enabled and used on arm arch. > Please Refer http://www.omappedia.org/wiki/Installing_and_Using_Ftrace > > Regards, > Rohan > Ok , thanks for the link . i will try the same . Regards Amit Nagal ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: regarding disable of CONFIG_DEBUG_FS
On Tue, Sep 20, 2011 at 10:21 AM, rohan puri wrote: > > > On Tue, Sep 20, 2011 at 10:09 AM, Amit Nagal wrote: >> >> Hi , >> >> i already tried manual editing . >> but when i call make to build image after manual edit , >> CONFIG_DEBUG_FS is turned on again . >> >> i tried manual editing in linux - x86 PC also . >> i manually edited arch/x86/configs/i386_defconfig file to disable >> CONFIG_DEBUG_FS , >> but when i call make to build image , CONFIG_DEBUG_FS is turned on again . >> > > > Ok. You can try commenting the CONFIG_DEBUG_FS from the Makefile of the > relevant kernel source which your module is interacting with. > Well i am doing the same for time being for my testing . but its not the right way to do and can't be adopted . Regards Amit Nagal ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: profiling functions called in interrupt context
On Tue, Sep 20, 2011 at 10:13 AM, Amit Nagal wrote: > On Tue, Sep 20, 2011 at 10:05 AM, rohan puri > wrote: > > > > > > On Tue, Sep 20, 2011 at 9:44 AM, Amit Nagal > wrote: > >> > >> Hi , > >> > >> i want to measure time spend in a callback function called from > >> interrupt context . > >> since the time spend will be in us / ns , what kernel apis can i use > >> to measure it ? > >> > >> also since i want to use it in interrupt context , kernel time > >> measurement apis should not sleep . > >> i am using embedded arm target , and tools like OProfile are not > >> available . > >> > >> can i be guided which kernel time measurement apis shall i use to > >> measure time in a interrupt callback ? > >> > >> Regards > >> Amit Nagal > > > > For this you can make use of ftrace. > > > > Refer link http://www.mjmwired.net/kernel/Documentation/trace/ftrace.txt > > > > Regards, > > Rohan > > > > Tools like ftrace are not available to me in my embedded arm target . > So i want to use kernel apis to deal with time measurement in > interrupt context . > > Regards > Amit Nagal > Hi Amit, I think ftrace can be enabled and used on arm arch. Please Refer http://www.omappedia.org/wiki/Installing_and_Using_Ftrace Regards, Rohan ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: regarding disable of CONFIG_DEBUG_FS
On Tue, Sep 20, 2011 at 10:09 AM, Amit Nagal wrote: > Hi , > > i already tried manual editing . > but when i call make to build image after manual edit , > CONFIG_DEBUG_FS is turned on again . > > i tried manual editing in linux - x86 PC also . > i manually edited arch/x86/configs/i386_defconfig file to disable > CONFIG_DEBUG_FS , > but when i call make to build image , CONFIG_DEBUG_FS is turned on again . > > Regards > Amit Nagal > > > > > > > On Tue, Sep 20, 2011 at 9:58 AM, rohan puri > wrote: > > > > On Tue, Sep 20, 2011 at 9:31 AM, Amit Nagal > wrote: > >> > >> Hi , > >> > >> i want to disable CONFIG_DEBUG_FS in my kernel configuration . > >> i am using 2.6.35 kernel on a embedded arm target . > >> i am using usb hid driver to fetch thumbnail data on usb hid interface . > >> > >> the reason why i want to disable CONFIG_DEBUG_FS is that > >> in interrupt callback , i dont want to spend time in debugging > >> functions which are enabled with CONFIG_DEBUG_FS . > >> > >> can i be guided how to do that ? its not possible to do using make > >> menuconfig though . > >> > >> Regards > >> > >> Amit Nagal > >> > >> ___ > >> Kernelnewbies mailing list > >> Kernelnewbies@kernelnewbies.org > >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > > > > Hi Amit, > > > > You can manually edit the .config file in the kernel source dir to > disable > > CONFIG_DEBUG_FS. > > > > Regards, > > Rohan. > > > Ok. You can try commenting the CONFIG_DEBUG_FS from the Makefile of the relevant kernel source which your module is interacting with. Regards, Rohan ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: profiling functions called in interrupt context
On Tue, Sep 20, 2011 at 10:05 AM, rohan puri wrote: > > > On Tue, Sep 20, 2011 at 9:44 AM, Amit Nagal wrote: >> >> Hi , >> >> i want to measure time spend in a callback function called from >> interrupt context . >> since the time spend will be in us / ns , what kernel apis can i use >> to measure it ? >> >> also since i want to use it in interrupt context , kernel time >> measurement apis should not sleep . >> i am using embedded arm target , and tools like OProfile are not >> available . >> >> can i be guided which kernel time measurement apis shall i use to >> measure time in a interrupt callback ? >> >> Regards >> Amit Nagal > > For this you can make use of ftrace. > > Refer link http://www.mjmwired.net/kernel/Documentation/trace/ftrace.txt > > Regards, > Rohan > Tools like ftrace are not available to me in my embedded arm target . So i want to use kernel apis to deal with time measurement in interrupt context . Regards Amit Nagal ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: regarding disable of CONFIG_DEBUG_FS
Hi , i already tried manual editing . but when i call make to build image after manual edit , CONFIG_DEBUG_FS is turned on again . i tried manual editing in linux - x86 PC also . i manually edited arch/x86/configs/i386_defconfig file to disable CONFIG_DEBUG_FS , but when i call make to build image , CONFIG_DEBUG_FS is turned on again . Regards Amit Nagal On Tue, Sep 20, 2011 at 9:58 AM, rohan puri wrote: > > On Tue, Sep 20, 2011 at 9:31 AM, Amit Nagal wrote: >> >> Hi , >> >> i want to disable CONFIG_DEBUG_FS in my kernel configuration . >> i am using 2.6.35 kernel on a embedded arm target . >> i am using usb hid driver to fetch thumbnail data on usb hid interface . >> >> the reason why i want to disable CONFIG_DEBUG_FS is that >> in interrupt callback , i dont want to spend time in debugging >> functions which are enabled with CONFIG_DEBUG_FS . >> >> can i be guided how to do that ? its not possible to do using make >> menuconfig though . >> >> Regards >> >> Amit Nagal >> >> ___ >> Kernelnewbies mailing list >> Kernelnewbies@kernelnewbies.org >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > Hi Amit, > > You can manually edit the .config file in the kernel source dir to disable > CONFIG_DEBUG_FS. > > Regards, > Rohan. > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: profiling functions called in interrupt context
On Tue, Sep 20, 2011 at 9:44 AM, Amit Nagal wrote: > Hi , > > i want to measure time spend in a callback function called from > interrupt context . > since the time spend will be in us / ns , what kernel apis can i use > to measure it ? > > also since i want to use it in interrupt context , kernel time > measurement apis should not sleep . > i am using embedded arm target , and tools like OProfile are not available > . > > can i be guided which kernel time measurement apis shall i use to > measure time in a interrupt callback ? > > Regards > Amit Nagal > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > Hi Amit, For this you can make use of ftrace. Refer link http://www.mjmwired.net/kernel/Documentation/trace/ftrace.txt Regards, Rohan ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: regarding disable of CONFIG_DEBUG_FS
On Tue, Sep 20, 2011 at 9:31 AM, Amit Nagal wrote: > Hi , > > i want to disable CONFIG_DEBUG_FS in my kernel configuration . > i am using 2.6.35 kernel on a embedded arm target . > i am using usb hid driver to fetch thumbnail data on usb hid interface . > > the reason why i want to disable CONFIG_DEBUG_FS is that > in interrupt callback , i dont want to spend time in debugging > functions which are enabled with CONFIG_DEBUG_FS . > > can i be guided how to do that ? its not possible to do using make > menuconfig though . > > Regards > > Amit Nagal > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > Hi Amit, You can manually edit the .config file in the kernel source dir to disable CONFIG_DEBUG_FS. Regards, Rohan. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
profiling functions called in interrupt context
Hi , i want to measure time spend in a callback function called from interrupt context . since the time spend will be in us / ns , what kernel apis can i use to measure it ? also since i want to use it in interrupt context , kernel time measurement apis should not sleep . i am using embedded arm target , and tools like OProfile are not available . can i be guided which kernel time measurement apis shall i use to measure time in a interrupt callback ? Regards Amit Nagal ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
regarding disable of CONFIG_DEBUG_FS
Hi , i want to disable CONFIG_DEBUG_FS in my kernel configuration . i am using 2.6.35 kernel on a embedded arm target . i am using usb hid driver to fetch thumbnail data on usb hid interface . the reason why i want to disable CONFIG_DEBUG_FS is that in interrupt callback , i dont want to spend time in debugging functions which are enabled with CONFIG_DEBUG_FS . can i be guided how to do that ? its not possible to do using make menuconfig though . Regards Amit Nagal ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Cannot read using USB Skeleton Driver
> You might be right and the code might be wrong, care to send a patch for > it correcting the issue? Would be glad to do that, if I am able to resolve the issue. Meanwhile, any insights from anybody on this would be welcome! Regards, Felix. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Why do the CFS chase fairness?
Hi . I am reaching my virtual limit here, so beg me pardon :) On Mon, Sep 19, 2011 at 23:26, Parmenides > Hmm..., does that mean timeslice weighting introduce unfainess? If we > think fairness relies on each task not fetching more timeslice than > other tasks, the eaiest way to achieve fairness is to give every task > the same timeslice. At the extreme theoritical side, yes, but again that is if all are CPU bound the complication comes since in reality most processes are mixture of CPU and I/O bound...or sometimes I/O bound only. > Can I understand like this: each task advance its progress tinier than > traditional timeslice, which makes C has more chances to be selected > to preempt A or B owing to its higher priority? Higer priority makes > C's virtual time smaller than A and B. > in non preemptive kernel i.e cooperative scheduling, your above suggested idea is the right way to achieve fairness in such situation. However, since user space (and now kernel space too) implements preemptive, adjusting time slice is not really necessary to make C kicks back into run queue. What the scheduler needs perhaps at this point is good priority recalculation is C could run ASAP. If not, even though C is in run queue, it still can beat the other processes in the competition of CPU time. -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: kernel crash dump analysis using crash utility
On Mon, Sep 19, 2011 at 13:56, amit mehta wrote: > ... > > --- --- > #19 [81a01da8] ret_from_intr at 8100bad3 > [exception RIP: acpi_check_resource_conflict+207] < --- could you post the complete log somewhere? BTW, looking at http://lxr.linux.no/#linux+v2.6.32.46/drivers/acpi/osl.c#L1177, looks like it is a procedure to find out potential conflict in ACPI..and maybe, in your case, it hits hard. -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Why do the CFS chase fairness?
Hi, > 2011/9/19 Mulyadi Santosa : > Hi :) > > Seriously, what I consider "more fair" is Con Kolivas BFS scheduler > these days. No excessive "time slice weighting", just priority > stepping and very strict deadline. > Hmm..., does that mean timeslice weighting introduce unfainess? If we think fairness relies on each task not fetching more timeslice than other tasks, the eaiest way to achieve fairness is to give every task the same timeslice. But this way seemingly can not be considered as fair. So, an exact definition of fairness will be appreciated. > I took this chance to add: to maximize throughput too... > > well, if you have processess let's say A, B, C. A and B are CPU bound, > C sleeps most of the times (let's say it's vim process running) > > If a scheduler implement very fair scheduling, then whenever user > press a key in vim window, C should be kicked in ASAP and then run. > However, as C yields its time slice, A or B should back ASAP too. > > If the scheduler is not really fair, then C should wait longer to be > back running. But C should not be given too much time so A and B have > more time to complete their number crunching works > Can I understand like this: each task advance its progress tinier than traditional timeslice, which makes C has more chances to be selected to preempt A or B owing to its higher priority? Higer priority makes C's virtual time smaller than A and B. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Why do the CFS chase fairness?
Hi :) On Mon, Sep 19, 2011 at 21:22, Parmenides wrote: > Well, even with the CFS scheduler, tasks still can have different > processor shares according to their priorities. Correct and agree :) > Conceptually, for > examp, suppose that there are three tasks with priorities 1, 2, 3, > respectively. For some fixed schedule period (targeted latency), which > determined by the number of tasks in run queue, the three tasks obtain > their CPU shares: 1/6, 2/6, 3/6 of the schedule period. Of course, in > reality, CPU share of each tasks also needs its weight (determined by > task's priority) be taken into account. correct again. This "weighting" mechanism is the core of making "fairness" happen...or at least approaching such situation. > So, I can not see the differences between traditional schedulers, > which are based on timeslice, and the CFS scheduler, which divide some > schedule period into shares in proportion to tasks' priorities. It > seems that both take the same effect. Neither do I :) Seriously, what I consider "more fair" is Con Kolivas BFS scheduler these days. No excessive "time slice weighting", just priority stepping and very strict deadline. >>> 2. Why do processes need fairness? >>> >> To achieve highest response time IMHO. > > How does fairness give tasks more higher response time? > I took this chance to add: to maximize throughput too... well, if you have processess let's say A, B, C. A and B are CPU bound, C sleeps most of the times (let's say it's vim process running) If a scheduler implement very fair scheduling, then whenever user press a key in vim window, C should be kicked in ASAP and then run. However, as C yields its time slice, A or B should back ASAP too. If the scheduler is not really fair, then C should wait longer to be back running. But C should not be given too much time so A and B have more time to complete their number crunching works Between A and B themselves should be balance somewhat, but not too short. Too short and they would spend more time switching to each other, too long and we would see they starve each other. Above are my interpretation, so pls CMIIW... -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Why do the CFS chase fairness?
2011/9/18 Mulyadi Santosa : > Hi... > > This would take us back to the days of comp science bachelor seat :) > >> >> 1. How to understand unfairness? > > IMHO, the easiest meaning is that: > one task gets proportionally more time slice than the other. Well, even with the CFS scheduler, tasks still can have different processor shares according to their priorities. Conceptually, for examp, suppose that there are three tasks with priorities 1, 2, 3, respectively. For some fixed schedule period (targeted latency), which determined by the number of tasks in run queue, the three tasks obtain their CPU shares: 1/6, 2/6, 3/6 of the schedule period. Of course, in reality, CPU share of each tasks also needs its weight (determined by task's priority) be taken into account. However, it is said that we can consider this manner of allocating CPU time is still fair because the scheduler approaches (at least approximately) user's intension, that is: tasks with different priorities get relevant CPU shares in terms of the their priorities. If so, IMHO it is also not hard for traditional schedulers to achieve fairness. For the above three tasks, the scheduler may allocate 5ms, 10ms, 15ms timeslice for each. That way, each task would receive the intended CPU shares as the CFS scheduler does. So, I can not see the differences between traditional schedulers, which are based on timeslice, and the CFS scheduler, which divide some schedule period into shares in proportion to tasks' priorities. It seems that both take the same effect. I think the clear idea of what fairness is may help us understand unfairness. > >> 2. Why do processes need fairness? >> > To achieve highest response time IMHO. How does fairness give tasks more higher response time? ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Cannot read using USB Skeleton Driver
On Mon, Sep 19, 2011 at 06:51:18PM +0530, Felix Varghese wrote: > Oh I don't think I have customized it to the point of breaking it. I > just modified the VID and PID to those of my device. And later, when I > noticed where it was getting stuck, I changed the wait_for_completion > to wait_for_completion_interruptible (in the code snippet quoted > previously) so that I could recover with Ctrl-C instead of a reboot. > And my hardware works fine with the usbserial driver you suggested (I > can read/write to it from a simple terminal program). But, to develop > a full-fledged driver, the skeleton driver seemed like a better > starting point, which is I am still trying to get it working. > > The condition which causes the code to wait for eternity (from the > line I quoted in one of my previous mails) seems to be: if > (!dev->processed_urb) > But I notice that this variable is not true even for the first read. > So the code seems to wait for the completion of something that has not > yet started. Also, I do not see this variable being explicitly set to > false either, anywhere within the driver. I may be on the wrong track, > but isn't this variable one that is used only within our driver? If > so, what exactly is it used for, considering that it is only set to 1 > (never to 0) and is 0 initially? You might be right and the code might be wrong, care to send a patch for it correcting the issue? thanks, greg k-h ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Cannot read using USB Skeleton Driver
Oh I don't think I have customized it to the point of breaking it. I just modified the VID and PID to those of my device. And later, when I noticed where it was getting stuck, I changed the wait_for_completion to wait_for_completion_interruptible (in the code snippet quoted previously) so that I could recover with Ctrl-C instead of a reboot. And my hardware works fine with the usbserial driver you suggested (I can read/write to it from a simple terminal program). But, to develop a full-fledged driver, the skeleton driver seemed like a better starting point, which is I am still trying to get it working. The condition which causes the code to wait for eternity (from the line I quoted in one of my previous mails) seems to be: if (!dev->processed_urb) But I notice that this variable is not true even for the first read. So the code seems to wait for the completion of something that has not yet started. Also, I do not see this variable being explicitly set to false either, anywhere within the driver. I may be on the wrong track, but isn't this variable one that is used only within our driver? If so, what exactly is it used for, considering that it is only set to 1 (never to 0) and is 0 initially? Regards, Felix. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: kernel crash dump analysis using crash utility
On Mon, Sep 19, 2011 at 12:26 PM, amit mehta wrote: > My Linux box just crashed while performing some network related tests. > I'm trying to analyze the kernel crash dump using "Crash" utility. > Need your help in analyzing it. > > <<>> > # crash /usr/lib/debug/lib/modules/2.6.32-131.0.15.el6.x86_64/vmlinux vmcore > .versioning information here... > .etc etc.. > KERNEL: /usr/lib/debug/lib/modules/2.6.32-131.0.15.el6.x86_64/vmlinux > DUMPFILE: vmcore [PARTIAL DUMP] > CPUS: 32 > DATE: Mon Sep 19 09:44:45 2011 < --- > UPTIME: 2 days, 22:55:44 > LOAD AVERAGE: 0.00, 0.02, 0.00 > TASKS: 409 > NODENAME: RHEL61ga > RELEASE: 2.6.32-131.0.15.el6.x86_64 > VERSION: #1 SMP Tue May 10 15:42:40 EDT 2011 > MACHINE: x86_64 (2660 Mhz) > MEMORY: 12 GB > PANIC: "Oops: [#1] SMP " (check log for details) > PID: 0 > COMMAND: "swapper" > TASK: 81a2d020 (1 of 8) [THREAD_INFO: 81a0] > CPU: 0 > STATE: TASK_RUNNING (ACTIVE) > WARNING: panic task not found > > stack trace frame 0 - frame 18 > here. > ... > > --- --- > #19 [81a01da8] ret_from_intr at 8100bad3 > [exception RIP: acpi_check_resource_conflict+207] < --- > RIP: 812bb86e RSP: 81a01e58 RFLAGS: 0206 > RAX: RBX: 81a01ec8 RCX: > RDX: 0006 RSI: RDI: 18f6 > RBP: 8100bace R8: R9: 0ca3 > R10: 88019aa061c2 R11: 88019aa06201 R12: 81b7c0b8 > R13: 0001 R14: 810ece03 R15: 81a01dd8 > ORIG_RAX: ffb5 CS: 0010 SS: 0018 > #20 [81a01e50] acpi_check_resource_conflict at 812bb851 > #21 [81a01ed0] show_current_driver at 813eccb7 > #22 [81a01ef0] cpu_idle at 81009e96 > > <<>> This same utility(crash) has an option of dumping system message buffer by invoking "log". For some reason, kernel message buffer did not got flushed on the disk and hence there were no relevant information on disk file. i.e. /var/log/messages. Using this same feature(log) i could find the perpetrator :) -Amit ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Cannot read using USB Skeleton Driver
On Mon, Sep 19, 2011 at 11:13:33AM +0530, Felix Varghese wrote: > > Just do: > > modprobe usb_serial vendor=0x product=0x > > with the proper vendor and product ids for your device, then plug it in. > > > > No kernel changes needed at all, just have a pair of bulk in/out > > endpoints and all will work automatically for you. > > Thanks Greg, I had thought that the usbserial driver would only work > with proper CDC class virtual COM devices. > I compiled it and tried it on my device and it worked fine! I was able > to do bidirectional communication. So at least now I can be sure that > one end is working. But the same device with the same firmware still > doesn't work with the (customized) usb-skeleton. What could be wrong? As I don't know what you customized exactly, nor how your hardware exactly works, I could not say, sorry. greg k-h ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: how to use hashmap in kernel module?
On Mon, Sep 19, 2011 at 9:23 AM, Jon Zhou wrote: > Hi > > I want to hashmap to store datat in kernel module, how can I do this? Any > existed code? Hello, There are a lot of places where hashes are used. Just grep for 'hash' through the kernel sources. For example have a look at futex_queues [1]. thanks, Daniel. [1] http://lxr.linux.no/linux+v3.0.4/kernel/futex.c#L150 ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
kernel crash dump analysis using crash utility
My Linux box just crashed while performing some network related tests. I'm trying to analyze the kernel crash dump using "Crash" utility. Need your help in analyzing it. <<>> # crash /usr/lib/debug/lib/modules/2.6.32-131.0.15.el6.x86_64/vmlinux vmcore .versioning information here... .etc etc.. KERNEL: /usr/lib/debug/lib/modules/2.6.32-131.0.15.el6.x86_64/vmlinux DUMPFILE: vmcore [PARTIAL DUMP] CPUS: 32 DATE: Mon Sep 19 09:44:45 2011 < --- UPTIME: 2 days, 22:55:44 LOAD AVERAGE: 0.00, 0.02, 0.00 TASKS: 409 NODENAME: RHEL61ga RELEASE: 2.6.32-131.0.15.el6.x86_64 VERSION: #1 SMP Tue May 10 15:42:40 EDT 2011 MACHINE: x86_64 (2660 Mhz) MEMORY: 12 GB PANIC: "Oops: [#1] SMP " (check log for details) PID: 0 COMMAND: "swapper" TASK: 81a2d020 (1 of 8) [THREAD_INFO: 81a0] CPU: 0 STATE: TASK_RUNNING (ACTIVE) WARNING: panic task not found stack trace frame 0 - frame 18 here. ... --- --- #19 [81a01da8] ret_from_intr at 8100bad3 [exception RIP: acpi_check_resource_conflict+207] < --- RIP: 812bb86e RSP: 81a01e58 RFLAGS: 0206 RAX: RBX: 81a01ec8 RCX: RDX: 0006 RSI: RDI: 18f6 RBP: 8100bace R8: R9: 0ca3 R10: 88019aa061c2 R11: 88019aa06201 R12: 81b7c0b8 R13: 0001 R14: 810ece03 R15: 81a01dd8 ORIG_RAX: ffb5 CS: 0010 SS: 0018 #20 [81a01e50] acpi_check_resource_conflict at 812bb851 #21 [81a01ed0] show_current_driver at 813eccb7 #22 [81a01ef0] cpu_idle at 81009e96 <<>> Observation: i) The panic hit at Sep 19 09:44:45 2011, and a peek inside /var/log/messages reveals that the machine was down for about 4-5 minutes around this timestamp. But there are no other relevant information available in the log file, so as printed in the panic string above: "Oops: [#1] SMP " (check log for details)", where else should i look for logs ? ii) Does frame 19:: [exception RIP: acpi_check_resource_conflict+207] and the immediated dump of the registers of my machine(Mine is x86_64) is an indication of where the Oops occured ? iii) Disassembly of "acpi_check_resource_conflict" at an offset:207 shows a 'test' instruction being carried out on CPU 0: 0x812bb86e : test %ebx,0xc4c3e8(%rip) # 0x81f07c5c iv) I belive that on 64 bit x86 machines, RIP represents EIP and similarly RBX represents EBX register. hence at the time of panic, the contents fo these registers were as follows: RBX = 81a01ec8 RIP = 812bb86e I don't know much of assembly, just did little bit of search on web, and my understanding is that the instruction "test %ebx,0xc4c3e8(%rip)" tells the processor to do the bitwise "and" of contents of ebx register with the value at the offset:0xc4c3e8 from the base address pointed by rip. i.e. 812bb86e+c4c3e8 = 81F07C56 ? Please correct me if I'm wrong. -Amit ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
