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Building kernel modules with debuginfo and printing line numbers in kernel oops message / coredump
by Sankar P April 21, 2013

April 21, 2013

Hi, I have written a kernel module which I build using: Makefile (edited a bit) ========== obj-m := simple.o simple-objs := s.o make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules ======= Everything builds fine. But my kernel module caused an oops and the message was something like: myfunctionname +0x2507 +5679 or some hexadecimal gibberish. I know that I can use some external tool to find out what these addresses mean. But, is there a way I can get the kernel oops message to print these information along with line number ? Is there a way to build the kernel module with debug symbols ? In user space, I usually do "-g" or "-ggdb" and it will give me line numbers and filenames neatly while dumping stacktrace. Is there a similar facility available for out of tree kernel modules too ? Even if I give : $ CFLAGS="-ggdb" make The output file size (.ko) is not changed. Can someone help me with building kernel modules with debug info and get the filename and line numbers printed in the oops messages / coredump ? Thanks. -- Sankar P http://psankar.blogspot.com

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YAFFS2 not part of Linux Kernel
by Pietro Paolini April 20, 2013

April 20, 2013

Hello all, reading docs and browsing internet I read that YAFFS2 is not merged in the Linux Kernel and that we should add it as a patch, the date is not write on that documents and I just tried to search YAFFS2 on the latest linux kernel source without relevant results. Then after a look on the www.yaffs.net I discovered a tutorial for merge it and I am sure, yes is not in the kernel tree. On the website they said is under the GPL license and I don't understand, why is not merged in the Linux Kernel directly ? It's just a curiosity, thanks in advance. Pietro.

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Check live Virtual Address to Physical Address mappings
by Shraddha Kamat April 19, 2013

April 19, 2013

I want to see live Virtual Addr. to Physical Addr. mappings for a process. is it possible to see such mappings ( for e.g. under /proc etc ..). Regards, Shraddha

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Why the niceness is not always taken into account ?
by Alexandre Laurent April 19, 2013

April 19, 2013

Hello, I have some questions about nice and programs scheduling. My machines have an 8 cores CPU. I am using an CPU intensive test, using OpenMP and running on the 8 cores for the experiments. When I am running my test it is taking around 12s. If I am starting at the same time two instances of this test it takes 24s which is totally fine and expected. I wanted to prioritize one instance of the test with nice. To do this, I am applying a niceness of -20 to privileged one, and setting a niceness of 20 to "slow down" the second one. This is usually working well. The privileged one with run around 12s (so, at full speed) and the other one 24s (-> paused for 12s and running the 12 last seconds at full speed). My problem is that in some cases it is not working at all. It works fine if I am running both programs in the same instance of the terminal, or from a script (so, same instance of interpreter). But this is not working if I am running the instances in separate SSH session. When I say it is not working, both instances will take 24s to run and the CPU usage is just shared between the tasks. More precisely : I am running the same test, but connecting twice on the remote machine (one connection by test instance). I am using exactly the same commands than during the others experiments. But, by using two SSH instances, the niceness will not be taken into account. The CPU will be shared equally between both instances even if htop is showing a niceness of 19 / -20 for the low priority program and the privileged program respectively. (For information, if I am running my program throught SSH using a script, and even by running the commands directly throught the SSH terminal it will work as expected. So, the cause is not on SSH.) Can you explain me, why in such case, the niceness is not taken into account ? Can you tell me how I can workaround this problem to effectively set niceness and get it respected by the system ? Best regards,

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help needed to do mmap
by er krishna April 19, 2013

April 19, 2013

Hi All, I am trying to do mmap from user space program to fetch physical memory base address B202E7000 and size F0. But I am getting operation not permitted error. Any suggestion by which I can increase the privilage by sysctl to acess this reason ? Krishna

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[ARM-LINUX]Init process is not getting launched while bringing up an opensource kernel on Qualcomm board...
by sandeep kumar April 19, 2013

April 19, 2013

Hi All I am doing a open-source kernel bringup on Qualcomm board. I reached till the successfull kernel initialization complete, and i can see the run_init_process() function executing successfully. But still i am not seeing my init process is not launched. Here are the following check points...i did, 1) I made a ramdisk image with the init process code, like this.... int main() { return 0; } 2) With the same ramdisk.img(which contains my init process(a return; statement in the main()) and another kernel i can see init process launch is successful. (in the kernel logs i am seeing panic message: Trying to kill init!! ) 3) In my bringup kernel, The similer kind of message is not seen. I can see ramdisk uncompression successful and also.. I have kept logs in arch/arm/kernel/sys_arm.c in the function kernel_execv() and i observed do_execv() function call is successful. Can anyone help me, am i missing something?? Please give me pointers on how to proceed. -- With regards, Sandeep Kumar Anantapalli,

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scheduler context
by ratheesh kannoth April 18, 2013

April 18, 2013

I would like to understand on linux scheduler context. I have read a lot in websites and i could find contradictory statement. There are so many mailing list also ,but with less info. I would really appreciate if anybody could spend some time answering my question. 1. Which context scheduler run ? ( process context or interrupt context ). 2. scheduler is the guy who picks up the next candidate to run. if it gets interrupted by hardirq, what will happen ? 3. if scheduler run in process context , how bottom half are scheduled ? 4. In smp, schedule() function may be called simultaneously. How it is handled ? 5. When a bottom half is interrupted by hard irq, how softirq kernel thread saves the state and restart it later ? ...what i mean is , an hardirq came and its isr executed. bottom half enabled and bottom half gets scheduled . Before bottom half is completed , next irq came and it enables bottom half , and the new bottom half is scheduled ....So here , what will happen to old bottom half , will it again run later ? Thanks, Ratheesh

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RE: linux-3.8.7 64bit build
by Giridhara RP (grp) April 18, 2013

April 18, 2013

I was using wrong compiler. 1. Changed compiler to 64bit 2. Changed Ld to 64 bit. So, its good if we run make command under linux 64 bit. From: Giridhara RP (grp) Sent: Thursday, April 18, 2013 1:42 PM To: 'kernelnewbies(a)kernelnewbies.org' Subject: linux-3.8.7 64bit build Hi, I am trying to build 64bit linux. .config file got created. But while compiling I get the error "unimplemented: 64-bit mode not compiled in". Any pointers much appreciated. Step2: bash-3.00$ make V=1 CC="gcc.c4.5.3-p0.linux" ARCH=x86_64 gcc.c4.5.3-p0.linux -Wp,-MD,kernel/.bounds.s.d -nostdinc -isystem /auto/sw/packages/gcc/c4.5.3-p0/i686-pc-linux/bin/../lib/gcc/i686-pc-linux/4.5.3/include -I/iws/grp-1/Linux_ker/linux-3.8.7/arch/x86/include -Iarch/x86/include/generated -Iinclude -I/iws/grp-1/Linux_ker/linux-3.8.7/arch/x86/include/uapi -Iarch/x86/include/generated/uapi -I/iws/grp-1/Linux_ker/linux-3.8.7/include/uapi -Iinclude/generated/uapi -include /iws/grp-1/Linux_ker/linux-3.8.7/include/linux/kconfig.h -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -Werror-implicit-function-declaration -Wno-format-security -fno-delete-null-pointer-checks -O2 -m64 -mno-red-zone -mcmodel=kernel -maccumulate-outgoing-args -DCONFIG_AS_CFI_SIGNAL_FRAME=1 -DCONFIG_AS_CFI_SECTIONS=1 -DCONFIG_AS_AVX=1 -pipe -Wno-sign-compare -fno-asynchronous-unwind-tables -fno-omit-frame-pointer -fno-optimize-sibling-calls -DCC_HAVE_ASM_GOTO -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(bounds)" -D"KBUILD_MODNAME=KBUILD_STR(bounds)" -fverbose-asm -S -o kernel/bounds.s kernel/bounds.c kernel/bounds.c:1:0: error: code model âkernelâ not supported in the 32 bit mode <===Error here kernel/bounds.c:1:0: sorry, unimplemented: 64-bit mode not compiled in <==== Error here make-3.79.1-p7[1]: *** [kernel/bounds.s] Error 1 make-3.79.1-p7: *** [prepare0] Error 2 bash-3.00$ Step1: bash-3.00$ make V=1 CC="gcc.c4.5.3-p0.x86elf" ARCH=x86_64 x86_64_defconfig make-3.79.1-p7 -f scripts/Makefile.build obj=scripts/basic rm -f .tmp_quiet_recordmcount mkdir -p include/linux include/config make-3.79.1-p7 -f scripts/Makefile.build obj=scripts/kconfig x86_64_defconfig scripts/kconfig/conf --defconfig=arch/x86/configs/x86_64_defconfig Kconfig # # configuration written to .config #

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linux-3.8.7 64bit build
by Giridhara RP (grp) April 18, 2013

April 18, 2013

Hi, I am trying to build 64bit linux. .config file got created. But while compiling I get the error "unimplemented: 64-bit mode not compiled in". Any pointers much appreciated. Step2: bash-3.00$ make V=1 CC="gcc.c4.5.3-p0.linux" ARCH=x86_64 gcc.c4.5.3-p0.linux -Wp,-MD,kernel/.bounds.s.d -nostdinc -isystem /auto/sw/packages/gcc/c4.5.3-p0/i686-pc-linux/bin/../lib/gcc/i686-pc-linux/4.5.3/include -I/iws/grp-1/Linux_ker/linux-3.8.7/arch/x86/include -Iarch/x86/include/generated -Iinclude -I/iws/grp-1/Linux_ker/linux-3.8.7/arch/x86/include/uapi -Iarch/x86/include/generated/uapi -I/iws/grp-1/Linux_ker/linux-3.8.7/include/uapi -Iinclude/generated/uapi -include /iws/grp-1/Linux_ker/linux-3.8.7/include/linux/kconfig.h -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -Werror-implicit-function-declaration -Wno-format-security -fno-delete-null-pointer-checks -O2 -m64 -mno-red-zone -mcmodel=kernel -maccumulate-outgoing-args -DCONFIG_AS_CFI_SIGNAL_FRAME=1 -DCONFIG_AS_CFI_SECTIONS=1 -DCONFIG_AS_AVX=1 -pipe -Wno-sign-compare -fno-asynchronous-unwind-tables -fno-omit-frame-pointer -fno-optimize-sibling-calls -DCC_HAVE_ASM_GOTO -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(bounds)" -D"KBUILD_MODNAME=KBUILD_STR(bounds)" -fverbose-asm -S -o kernel/bounds.s kernel/bounds.c kernel/bounds.c:1:0: error: code model âkernelâ not supported in the 32 bit mode <===Error here kernel/bounds.c:1:0: sorry, unimplemented: 64-bit mode not compiled in <==== Error here make-3.79.1-p7[1]: *** [kernel/bounds.s] Error 1 make-3.79.1-p7: *** [prepare0] Error 2 bash-3.00$ Step1: bash-3.00$ make V=1 CC="gcc.c4.5.3-p0.x86elf" ARCH=x86_64 x86_64_defconfig make-3.79.1-p7 -f scripts/Makefile.build obj=scripts/basic rm -f .tmp_quiet_recordmcount mkdir -p include/linux include/config make-3.79.1-p7 -f scripts/Makefile.build obj=scripts/kconfig x86_64_defconfig scripts/kconfig/conf --defconfig=arch/x86/configs/x86_64_defconfig Kconfig # # configuration written to .config #

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Re: Build error in linux-3.8.7
by Sarbojit Ganguly April 18, 2013

April 18, 2013

On 18 April 2013 09:22, Giridhara RP (grp) <grp(a)cisco.com> wrote: > Hi Sarbojit,**** > > ** ** > > Builng kernel with gcc-4.5+ solved all the major issues (compile error and > Segmentation Fault). Regarding bnx2, our board does not have bnx2. So, I > commented ‘CONFIG_BNX2’ in .config file. > Good :-) > **** > > ** ** > > Thanks**** > > Giri**** > > ** ** > > *From:* Sarbojit Ganguly [mailto:unixman.linuxboy@gmail.com] > *Sent:* Wednesday, April 17, 2013 5:43 PM > > *To:* Giridhara RP (grp) > *Cc:* kernelnewbies(a)kernelnewbies.org > *Subject:* Re: Build error in linux-3.8.7**** > > ** ** > > ** ** > > ** ** > > On 17 April 2013 15:38, Giridhara RP (grp) <grp(a)cisco.com> wrote:**** > > Thanks guys J. Finally I have a successful build.**** > > ** ** > > Sorry, checked late, do share the reason and solution. It might help > others who are facing similar problem. > > **** > > Giri**** > > **** > > *From:* kernelnewbies-bounces(a)kernelnewbies.org [mailto: > kernelnewbies-bounces(a)kernelnewbies.org] *On Behalf Of *Giridhara RP (grp) > *Sent:* Wednesday, April 17, 2013 1:42 PM**** > > > *To:* Sarbojit Ganguly > *Cc:* kernelnewbies(a)kernelnewbies.org > *Subject:* RE: Build error in linux-3.8.7**** > > **** > > Hi,**** > > **** > > I am getting error in firmware. Any pointer will be helpful. Segmetation > fault is gone after changning to gcc-4.5**** > > **** > > make-3.79.1-p7[1]: Nothing to be done for `all'.**** > > CHK include/generated/uapi/linux/version.h**** > > make-3.79.1-p7[1]: Nothing to be done for `relocs'.**** > > CHK include/generated/utsrelease.h**** > > CALL scripts/checksyscalls.sh**** > > *make-3.79.1-p7[1]: *** No rule to make target `|', needed by > `firmware/bnx2/bnx2-mips-09-6.2.1a.fw.gen.S'. Stop.***** > > *make-3.79.1-p7: *** [firmware] Error 2***** > > make-3.79.1-p7: *** Waiting for unfinished jobs....**** > > CHK include/generated/compile.h**** > > PASYMS arch/x86/realmode/rm/pasyms.h**** > > VDSOSYM arch/x86/vdso/vdso32-int80-syms.lds**** > > LDS arch/x86/realmode/rm/realmode.lds**** > > LD arch/x86/realmode/rm/realmode.elf**** > > RELOCS arch/x86/realmode/rm/realmode.relocs**** > > OBJCOPY arch/x86/realmode/rm/realmode.bin**** > > VDSOSYM arch/x86/vdso/vdso32-sysenter-syms.lds**** > > AS arch/x86/realmode/rmpiggy.o**** > > VDSOSYM arch/x86/vdso/vdso32-syms.lds**** > > LD arch/x86/realmode/built-in.o**** > > LD arch/x86/vdso/built-in.o**** > > LD arch/x86/built-in.o**** > > make-3.79.1-p7: *** wait: No child processes. Stop.**** > > bash-3.00$**** > > **** > > Thanks**** > > Giri**** > > **** > > *From:* kernelnewbies-bounces(a)kernelnewbies.org [ > mailto:kernelnewbies-bounces@kernelnewbies.org<kernelnewbies-bounces(a)kernelnewbies.org>] > *On Behalf Of *Giridhara RP (grp) > *Sent:* Wednesday, April 17, 2013 12:33 PM > *To:* Sarbojit Ganguly > *Cc:* kernelnewbies(a)kernelnewbies.org > *Subject:* RE: Build error in linux-3.8.7**** > > **** > > Hi Sarbojit,**** > > **** > > Using gcc4.2.1 the compilation error disaappered, but now linker (ld) is > crashing. Any workaround to overcome this?**** > > **** > > CHK include/generated/uapi/linux/version.h**** > > CHK include/generated/utsrelease.h**** > > CALL scripts/checksyscalls.sh**** > > CHK include/generated/compile.h**** > > LD arch/x86/kernel/built-in.o**** > > /bin/sh: line 1: 17454 Segmentation fault ld -m elf_i386 -r -o > arch/x86/kernel/built-in.o arch/x86/kernel/process_32.o > arch/x86/kernel/signal.o arch/x86/kernel/entry_32.o arch/x86/kernel/traps.o > arch/x86/kernel/irq.o arch/x86/kernel/irq_32.o > arch/x86/kernel/dumpstack_32.o arch/x86/kernel/time.o > arch/x86/kernel/ioport.o arch/x86/kernel/ldt.o arch/x86/kernel/dumpstack.o > arch/x86/kernel/nmi.o arch/x86/kernel/setup.o arch/x86/kernel/x86_init.o > arch/x86/kernel/i8259.o arch/x86/kernel/irqinit.o > arch/x86/kernel/jump_label.o arch/x86/kernel/irq_work.o > arch/x86/kernel/probe_roms.o arch/x86/kernel/i386_ksyms_32.o > arch/x86/kernel/syscall_32.o arch/x86/kernel/bootflag.o > arch/x86/kernel/e820.o arch/x86/kernel/pci-dma.o arch/x86/kernel/quirks.o > arch/x86/kernel/topology.o arch/x86/kernel/kdebugfs.o > arch/x86/kernel/alternative.o arch/x86/kernel/i8253.o > arch/x86/kernel/pci-nommu.o arch/x86/kernel/hw_breakpoint.o > arch/x86/kernel/tsc.o arch/x86/kernel/io_delay.o arch/x86/kernel/rtc.o > arch/x86/kernel/pci-iommu_table.o arch/x86/kernel/resource.o > arch/x86/kernel/process.o arch/x86/kernel/i387.o arch/x86/kernel/xsave.o > arch/x86/kernel/ptrace.o arch/x86/kernel/tls.o arch/x86/kernel/step.o > arch/x86/kernel/i8237.o arch/x86/kernel/stacktrace.o > arch/x86/kernel/cpu/built-in.o arch/x86/kernel/acpi/built-in.o > arch/x86/kernel/reboot.o arch/x86/kernel/msr.o arch/x86/kernel/cpuid.o > arch/x86/kernel/early-quirks.o arch/x86/kernel/smp.o > arch/x86/kernel/smpboot.o arch/x86/kernel/tsc_sync.o > arch/x86/kernel/setup_percpu.o arch/x86/kernel/mpparse.o > arch/x86/kernel/apic/built-in.o arch/x86/kernel/reboot_fixups_32.o > arch/x86/kernel/trace_clock.o arch/x86/kernel/machine_kexec_32.o > arch/x86/kernel/relocate_kernel_32.o arch/x86/kernel/crash.o > arch/x86/kernel/crash_dump_32.o arch/x86/kernel/kprobes.o > arch/x86/kernel/kprobes-opt.o arch/x86/kernel/module.o > arch/x86/kernel/doublefault_32.o arch/x86/kernel/vm86_32.o > arch/x86/kernel/early_printk.o arch/x86/kernel/hpet.o > arch/x86/kernel/amd_nb.o arch/x86/kernel/pcspeaker.o > arch/x86/kernel/microcode.o arch/x86/kernel/check.o > arch/x86/kernel/perf_regs.o**** > > make-3.79.1-p7[2]: *** [arch/x86/kernel/built-in.o] Error 139**** > > make-3.79.1-p7[1]: *** [arch/x86/kernel] Error 2**** > > make-3.79.1-p7: *** [arch/x86] Error 2**** > > **** > > bash-3.00$ uname -a**** > > Linux sam-build01.cisco.com 2.6.9-89.ELsmp #1 SMP Mon Jun 22 12:32:43 EDT > 2009 i686 i686 i386 GNU/Linux**** > > **** > > bash-3.00$ ld --version**** > > GNU ld version 2.15.92.0.2 20040927**** > > Copyright 2002 Free Software Foundation, Inc.**** > > This program is free software; you may redistribute it under the terms of* > *** > > the GNU General Public License. This program has absolutely no warranty.* > *** > > **** > > *From:* kernelnewbies-bounces(a)kernelnewbies.org [ > mailto:kernelnewbies-bounces@kernelnewbies.org<kernelnewbies-bounces(a)kernelnewbies.org>] > *On Behalf Of *Giridhara RP (grp) > *Sent:* Wednesday, April 17, 2013 11:35 AM > *To:* Sarbojit Ganguly > *Cc:* kernelnewbies(a)kernelnewbies.org > *Subject:* RE: Build error in linux-3.8.7**** > > **** > > Hi Sarbojit,**** > > **** > > My gcc is 3.4.6-11. Sure, I will try 3.8.8**** > > **** > > bash-3.00$ gcc --version**** > > gcc (GCC) 3.4.6 20060404 (Red Hat 3.4.6-11)**** > > Copyright (C) 2006 Free Software Foundation, Inc.**** > > This is free software; see the source for copying conditions. There is NO > **** > > warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. > **** > > **** > > *From:* Sarbojit Ganguly [mailto:unixman.linuxboy@gmail.com<unixman.linuxboy(a)gmail.com>] > > *Sent:* Wednesday, April 17, 2013 11:34 AM > *To:* Giridhara RP (grp) > *Cc:* kernelnewbies(a)kernelnewbies.org > *Subject:* Re: Build error in linux-3.8.7**** > > **** > > Hello GRP,**** > > **** > > Can you post your toolchain (gcc) version? As you're doing this, may I > request you to try with 3.8.8?**** > > **** > > Regards,**** > > Sarbojit**** > > **** > > On 17 April 2013 10:20, Giridhara RP (grp) <grp(a)cisco.com> wrote:**** > > Hi,**** > > **** > > I am new to linux kernel buidling. I have download 3.8.7 latest (stable) > kernel from https://www.kernel.org/. I want build kernel for X86_64.**** > > **** > > 1. make x86_64_defconfig (this created .config file)**** > > 2. make**** > > Make failed with below error, please help me in resolving this.**** > > **** > > CC kernel/power/user.o**** > > CC kernel/power/block_io.o**** > > CC kernel/power/poweroff.o**** > > LD kernel/power/built-in.o**** > > CC kernel/sched/core.o**** > > CC kernel/sched/clock.o**** > > CC kernel/sched/cputime.o**** > > CC kernel/sched/idle_task.o**** > > CC kernel/sched/fair.o**** > > kernel/sched/fair.c: In function `update_curr':**** > > kernel/sched/fair.c:428: sorry, unimplemented: inlining failed in call to > 'account_cfs_rq_runtime': function body not available**** > > kernel/sched/fair.c:714: sorry, unimplemented: called from here**** > > make-3.79.1-p7[2]: *** [kernel/sched/fair.o] Error 1**** > > make-3.79.1-p7[1]: *** [kernel/sched] Error 2**** > > make-3.79.1-p7: *** [kernel] Error 2**** > > bash-3.00$ pwd**** > > **** > > thanks**** > > Giri**** > > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies(a)kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies**** > > > > **** > > **** > > -- > Regards, > Sarbojit **** > > > > > -- > Regards, > Sarbojit **** > -- Regards, Sarbojit

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