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

Re: kernel list data structure
by Amirali Shambayati June 6, 2011

June 6, 2011

As I have read this pdf, I think I have assigned them right. I don't know what's wrong? :-? https://prof.hti.bfh.ch/myf1/adv-linux/courseNotes/*klist*-*intro*-1.3.*pdf* On Mon, Jun 6, 2011 at 10:52 AM, Amirali Shambayati < amirali.shambayati(a)gmail.com> wrote: > As I have read the attached pdf, I think I have assigned them right. I > don't know what's wrong? :-? > > > On Mon, Jun 6, 2011 at 10:43 AM, Amirali Shambayati < > amirali.shambayati(a)gmail.com> wrote: > >> Ali thanks for your valuable comments. Would you suggest me an alternative >> method to implement the structure I explained? >> >> >> On Mon, Jun 6, 2011 at 10:05 AM, Ali Bahar <ali(a)internetdog.org> wrote: >> >>> >>> All right, let's take another stab at this. >>> >>> > list. But as I debugged my code, it seems that my concept is wrong. >>> Would >>> > anyone guide me how to implement a two-dimensioned list, or introduce >>> me a >>> >>> >>> My interpretation of what you got is as follows, based on what you've >>> said you'll be assigning each list_head to: >>> >>> struct noop_data { >>> struct list_head readQueue; // You haven't explicitly stated which >>> // LL this will be assigned to. >>> struct list_head writeQueue;// The head of a LL of 'struct bundle' >>> // nodes. >>> struct bundle { >>> int bundleNumber; >>> int size; >>> struct list_head bundlesQueue; // The LL of 'struct bundle' >>> struct list_head reqsQueue; // The head of a LL of >>> // 'struct request'? >>> int filled[8]; >>> } bun; >>> unsigned int starved; >>> }; >>> >>> Depending on how you're going to assign these, you may end up with >>> spaghetti. As I indicated before, the nested inclusion of 'struct >>> bundle' is likely wrong. >>> >>> later, >>> ali >>> >>> >>> > "noop_data" has a reference to start point of bundles list, called >>> > "writeQueue" >>> > "bundle" has a reference to start point of requests list, called >>> > "reqsQueue". >>> > "bundle" knows its related list using "bundlesQueue". >>> > "request" knows its related list using "queuelist". (request struct is >>> > already implemented in kernel) >>> > >>> > struct bundle { >>> > int bundleNumber; >>> > int size; >>> > struct list_head bundlesQueue; >>> > struct list_head reqsQueue; >>> > int filled[8]; >>> > }; >>> > >>> > struct noop_data { >>> > struct list_head readQueue; >>> > struct list_head writeQueue; >>> > struct bundle bun; >>> > unsigned int starved; >>> > }; >>> >> >> >> >> -- >> Amirali Shambayati >> Bachelor Student >> Computer Engineering Department >> Sharif University of Technology >> Tehran, Iran >> >> > > > -- > Amirali Shambayati > Bachelor Student > Computer Engineering Department > Sharif University of Technology > Tehran, Iran > > -- Amirali Shambayati Bachelor Student Computer Engineering Department Sharif University of Technology Tehran, Iran

2 2

Regarding Edac support on E8400 processor.
by nilesh June 6, 2011

June 6, 2011

Hi, I am trying to enable and test EDAC functionality on my desktop running 2.6.39 kernel. But I do not see any EDAC support in /sys/devices (e.g. support for parity errors enable/disable for PCI devices etc.). Could someone please advice if I am missing anything? Is EDAC completely not supported for E8400 (I do not see the kernel module for this one)? -- Thanks, Nilesh P.S. Below are few of the details: * CPU information root@nilesh-desktop:linux-2.6.39 # cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 23 model name : Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz stepping : 10 cpu MHz : 2000.000 cache size : 6144 KB * EDAC modules I tried to insert and were inserted without error. root@nilesh-desktop:linux-2.6.39 # lsmod | grep -i EDAC i7300_edac 12270 0 r82600_edac 3686 0 i5100_edac 5847 0 i5400_edac 12136 0 i5000_edac 13402 0 e7xxx_edac 5085 0 e752x_edac 11985 0 i7core_edac 21192 0 edac_core 55426 8 i7300_edac,r82600_edac,i5100_edac,i5400_edac,i5000_edac,e7xxx_edac,e752x_edac,i7core_edac * Config file snippet. root@nilesh-desktop:linux-2.6.39 # cat .config | grep EDAC CONFIG_EDAC=y CONFIG_EDAC_DEBUG=y # CONFIG_EDAC_DECODE_MCE is not set CONFIG_EDAC_MM_EDAC=m CONFIG_EDAC_MCE=y CONFIG_EDAC_AMD76X=m CONFIG_EDAC_E7XXX=m CONFIG_EDAC_E752X=m CONFIG_EDAC_I82875P=m CONFIG_EDAC_I82975X=m CONFIG_EDAC_I3000=m CONFIG_EDAC_I3200=m CONFIG_EDAC_X38=m CONFIG_EDAC_I5400=m CONFIG_EDAC_I7CORE=m CONFIG_EDAC_I82860=m CONFIG_EDAC_R82600=m CONFIG_EDAC_I5000=m CONFIG_EDAC_I5100=m CONFIG_EDAC_I7300=m

1 0

Problems with disabling Optimization
by Prabhu nath June 6, 2011

June 6, 2011

Dear All, Disabling O2 and Os on Kernel building, I am getting the following error. Can you please help me in debugging this. Saw some info on the net, but could not resolve it. ERROR: "intel_gmbus_is_forced_bit" [drivers/gpu/drm/i915/i915.ko] undefined! ERROR: "__udivdi3" [drivers/gpu/drm/i915/i915.ko] undefined! make[2]: *** [__modpost] Error 1 make[1]: *** [modules] Error 2 make: *** [sub-make] Error 2 Regards, Prabhu

3 3

reading a core's current task from memory
by linkerndbg June 5, 2011

June 5, 2011

Hi dear list members, I'm maintaining a Linux kernel debugger through jtag that has been doing quite well on unicore/SH4 systems so far, now I'd like to support ARM/SMP systems and do some improvements: I'm looking for a simple way to know which is the current task executing on one each core by accessing memory from jtag. Knowing a core's current when it is running kernel core is easy as the sp registers gives direct access to the current thread_info, now suppose a core is running a usermode code page, then sp and pc are virtual memory. through the jtag interface I can access any symbol which offset I know from the vmlinux symbol table, and any field which offset is not dependent of the configure options for a given kernel version. Sadly I can't easily access the per_cpu runqueues and the rq->curr field this way. I'd be grateful for any suggestion as of how to do ! many thanks, M.

1 0

with 3.0.0-rc1 kernel, my sound has suddenly vanished
by Robert P. J. Day June 5, 2011

June 5, 2011

just built and booted to a 3.0.0-rc1-00180-g0792644-dirty kernel, where the only diff from mainstream is a hack to get around the i915 "black screen of death" issue. annoyingly, my sound has suddenly vanished. about to start diagnosing but if anyone has any suggestions, i'm all ears. gateway laptop, running updated ubuntu 10.10. partial output from "lspci -v": 00:1b.0 Audio device: Intel Corporation 5 Series/3400 Series Chipset High Definition Audio (rev 05) Subsystem: Acer Incorporated [ALI] Device 031c Flags: bus master, fast devsel, latency 0, IRQ 42 Memory at d4400000 (64-bit, non-prefetchable) [size=16K] Capabilities: <access denied> Kernel driver in use: HDA Intel Kernel modules: snd-hda-intel rday -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================

1 0

sysrq-c oops results in hang, not reboot. panic_on_oops=1.
by Ali Bahar June 4, 2011

June 4, 2011

Hi all, I do a sysrq-c in order to force an oops crash. It works (as it always has), and dumps the stack. However, it hangs indefinitely, no longer rebooting. kernel.panic_on_oops=1, and kernel.panic=0. Is there anything else which determines the behaviour at this point? Thank you, in advance, for any insights, ali PS I _have_ gotten this stuff (incl. kdump) to work before. PPS I'd run into this before, a while ago, but did not tend to it till now, when I _have to_! :-) I'm getting a very reproducible crash (of 2.6.39-rc3 code which I have not touched), and would like to get an idea of the cause. Mind you, that just hangs the box, so the above will not be of direct help.

1 0

Re: kernel memory allocation
by João Eduardo Luís June 3, 2011

June 3, 2011

Hi. In future replies, please CC the list. Does it panic in during the kmalloc, or afterwards? Are you checking if 'newBun' is NULL? I may be missing something obvious in that code, but unless you are out of memory or with some past corruption, I don't think that should panic the kernel. In any case, the panic trace should help. Cheers. --- João Eduardo Luís gpg key: 477C26E5 from pool.keyserver.eu On Jun 3, 2011, at 7:50 PM, Amirali Shambayati wrote: > thanks for your guidance. I just want to allocate memory for a struct. I use this: > > struct bundle* newBun; > newBun = kmalloc(sizeof(*newBun), GFP_KERNEL); > > but it goes to panic state. > > 2011/6/3 João Eduardo Luís <jecluis(a)gmail.com> > Hi. > > From [1] I'm lead to believe the only difference between the regular kmalloc() arguments and those of kmalloc_node() is the one specifying which node you want to allocate the memory on. > > Aside from the third argument, which seems to be related with NUMA (with which I never worked on kernel-context), I would suggest you to read [2]. > > If on the other hand you only want to allocate memory locally, maybe you should use kmalloc() or one of its variants [3]. > > > Cheers. > > > [1] - http://www.kernel.org/doc/htmldocs/kernel-api/API-kmalloc-node.html > [2] - http://www.kernel.org/doc/htmldocs/kernel-api/API-kcalloc.html > [3] - http://www.kernel.org/doc/htmldocs/kernel-api/mm.html#id408507 > --- > João Eduardo Luís > gpg key: 477C26E5 from pool.keyserver.eu > > > > > > On Jun 3, 2011, at 7:07 PM, Amirali Shambayati wrote: > > > > > Hello all, > > > > I just want to allocate memory for a struct instantiation. Would anyone guide me what arguments I should pass to "kmalloc_node"? > > Regards, > > -- > > Amirali Shambayati > > Bachelor Student > > Computer Engineering Department > > Sharif University of Technology > > Tehran, Iran > > > > _______________________________________________ > > Kernelnewbies mailing list > > Kernelnewbies(a)kernelnewbies.org > > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > > > -- > Amirali Shambayati > Bachelor Student > Computer Engineering Department > Sharif University of Technology > Tehran, Iran >

2 1

Re: kernel memory allocation
by João Eduardo Luís June 3, 2011

June 3, 2011

Hello, Once again, I would pretty much enjoy if you CC'ed the list on replies. On Jun 3, 2011, at 8:49 PM, Amirali Shambayati wrote: > I set breakpoint before kmalloc. panic happens after kmalloc. > >> 2011/6/4 Amirali Shambayati <amirali.shambayati(a)gmail.com> >> ofcourse it's null before allocate it. I make an instantiation of it. then I want to allocate memory for it.What else I should do? I meant, are you checking if 'newBun' is NULL _AFTER_ the kmalloc? The kmalloc call will return NULL instead of a pointer to newly allocated memory whenever an error occurs. If by any chance you are not checking if 'newBun' is NULL after the kmalloc, then you should do it. Also, if the panic happens _after_ the kmalloc, and not _during_ the kmalloc, I would say there's a slim chance of kmalloc being the cause of the panic. --- João Eduardo Luís gpg key: 477C26E5 from pool.keyserver.eu

1 0

kernel memory allocation
by Amirali Shambayati June 3, 2011

June 3, 2011

Hello all, I just want to allocate memory for a struct instantiation. Would anyone guide me what arguments I should pass to "kmalloc_node"? Regards, -- Amirali Shambayati Bachelor Student Computer Engineering Department Sharif University of Technology Tehran, Iran

2 1

Calling printk with locks held
by Neil Baylis June 2, 2011

June 2, 2011

I've just been told that it's not OK to call printk while holding a lock. This came as a surprise to me, as I've written thousands of lines of code that calls printk while holding multiple locks, and have not seen any problem. The only explanation I was given was that it can deadlock. Is this correct? I thought there were very few places where it was not safe to call printk. Neil Baylis

3 2