'Domain'에 해당되는 글 103건

  1. 2011.04.21 [GNU] Issues of cross-compiling in GNU build system.
  2. 2011.04.20 [Android] Handling kernel device uevent in userspace.
  3. 2011.04.19 [Kernel] kobject uevent in kernel
  4. 2011.04.19 [Kernel] Creating user-space process in Kernel
  5. 2011.04.14 windowsXP 에서 모든 동영상이 흑백으로만 재생될때...
  6. 2011.03.18 [Android][GNU] establishing gnu system root on android devices
  7. 2011.03.18 [Ubuntu] C-s and C-q doesn't work in gnorm-terminal
  8. 2011.02.15 [Android] NDK issues (found)
  9. 2011.01.19 [Ubuntu] visual effect doens't work with Nvidia driver...
  10. 2010.11.29 [Linux] Writing input event directly.

[GNU] Issues of cross-compiling in GNU build system.

Domain/Software 2011.04.21 19:23

* It is impossible to get full supporting from 'configure'

Getting runtime informations - ex bytes of 'long' type, checking whether symbol 'xxx' is in the library or not. - is impossible.
-> Some releases complain this and doesn't proceed anymore.

* Some releases still refer /lib, /usr/lib, /usr/include etc.

* Using 'make check' in naive way is impossible.

* Anything else???

tags : cross-compile, GNU
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[Android] Handling kernel device uevent in userspace.

Domain/Android 2011.04.20 09:53
⚫ ueventd
    ⚬ ueventd creates and 'poll' netlink socket.
        ueventd_main [init/ueventd.c]

    ⚬ read kernel event message -> parse -> handle
        handle_device_event [init/devices.c]
            -> device_changed [init/init.c]
                -> queue_device_triggers [init/init_parser.c]
        : search action list to know what to do for this event.
          searching action which name is device-added/removed-[device node].
          [device node] is from 'DEVPATH' variable of uevent message.

    ⚬ action list : list declared at [init_parser.c]
        • builtin action (added by 'queue_builtin_action [init/init_parser.c]')
            ex. property_init, wait_for_coldboot_done etc.
        • from script (added by 'parse_action [init/init_parser.c]')
            section "on device-added-[device path] / on device-removed-[device path]"
                on device-added-/dev/block/mmcblk0p18
                    exec /system/bin/sh /system/bin/hello_mmc.sh

⚫ other daemons (ex usbd)
    ⚬ create and 'poll' netlink socket.
tags : uevent
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[Kernel] kobject uevent in kernel

Domain/Kernel 2011.04.19 19:12
⚫ Sendig kobject uevent to user space from kernel
    ⚬ Concept
        • Execute user-space binary with predefined + customized environment variables.
        • Send message to pre-defined netlink socket unit created by kernel.

    ⚬ From souce code (hotplug)
        • kernel node [kernel/sysctl.c]
        : /proc/sys/kernel/hotplug

        • kobject_uevent_env() [kobject_uevent.c]
            default user process executable image path
                -> CONFIG_UEVENT_HELPER_PATH
        • kernel/sysctl.c
            'uevent_helper' value can be RWed through 'hotplug' node of sysctl.

    ⚬ From souce code (netlink)
        • kobject_uevent_env() [kobject_uevent.c]
            : #if defined(CONFIG_NET)
            write message to netlink socket unit (NETLINK_KOBJECT_UEVENT)
        • netlink.h
            netlink units
        • Creating in userspace
tags : kobject, uevent
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[Kernel] Creating user-space process in Kernel

Domain/Kernel 2011.04.19 15:59
⚬ Concept
    - Creating Kernel Thread
    - Fork by call 'do_fork' directly (because, this is inside kernel!)
    - Exec by call 'do_execve'

⚬ Code walkthrough
    • kmod.h
        call_usermodehelper / call_usermodehelper_fns

    • kmod.c
            -> setup subprocess infos.
                : path to execute, arguments, env variables etc
            -> set 'work' function of 'workqueue' to '__call_usermodehelper'
                : INIT_WORK(&sub_info->work, __call_usermodehelper);
            -> setup subprocess functions
            -> queue this work to 'khelper_wq' workqueue.
        __call_usermodehelper() /* <- in work queue (khelper_wq) */
            pid = kernel_thread(___call_usermodehelper, sub_info, CLONE_VFORK | SIGCHILD);
            : set pc to 'kernel_thread_helper'- assembly function
            pid = do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
            : Shuffle the arument into the correct register before calling the thread function
            : set pc to given thread function (in this example, '___call_usermodehelper()' function.)
            kernel_execve(sub_info->path, sub_info->argv, sub_info->envp);

    • sys_arm.c
            : make it to user space process!
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windowsXP 에서 모든 동영상이 흑백으로만 재생될때...

Domain/Win32 2011.04.14 18:08
codec을 재 설치해도, GOM player, KMP등을 지우고 재설치해도 해결이 안되었는데,
KMP를 실행하고 '컨트롤 박스..(Alt+G)'를 실행하니,  'COLORS' tab의 HW controls 부분에서 3개의 설정중 제일 위의 것이 가장 좌측으로 설정되어 있었는데, 이걸 중간으로 옮기니 문제가 해결되었다. 자세한 내용은 좀더 분석이 필요..~~~
(귀차니즘에... 과연 내가 더 분석을 하긴 할까나... -_-; )
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[Android][GNU] establishing gnu system root on android devices

Domain/Android 2011.03.18 06:40

This article is to describe summary and some important points to establish gnu system root on android devices based on my experience.

    [] : version used.

    Now a days, performance of Android mobile device is much like PC.
    So, why don't you use Android device just like linux desktop?
    As a first step, here is summary to construct gnu system root on Android device.

Setup Sequence
    Installing cross compiling tools
        *** NOTE ****************************************************************
        *    Followings are not tested because I just used built Sourcery g++.  *
        *    [ Codesourcery 2007q3-53 ]                                         *
        * Reference : http://frank.harvard.edu/~coldwell/toolchain/
        * Build GNU binutils
            - Using '--disable-nls' option is recommended (to reduce compile time and dependency.
        * Install Linux Kernel Headers
            - Latest Sourcery g++(2010.09-50) supports only at-least-2.6.16-target-kernel.
        * Build GLIBC headers
        * Build GCC for headers:
            - Using '--disable-nls --without-headers' is recommended.
            - example : configure option of GCC in Codesourcery 2007q3-53
                /vobs/linuxjava/cs_toolchain/mycstc/cs_build_dir/src/gcc-4.2/configure --build=i686-pc-linux-gnu
                  --host=i686-pc-linux-gnu --target=arm-none-linux-gnueabi --enable-threads --disable-libmudflap
                  --disable-libssp --disable-libgomp --disable-libstdcxx-pch --with-gnu-as --with-gnu-ld
                  --enable-languages=c,c++ --enable-shared --enable-symvers=gnu --enable-__cxa_atexit
                  --with-pkgversion=CodeSourcery Sourcery G++ Lite 2007q3-53
                  --disable-nls --prefix=/opt/codesourcery --with-sysroot=/opt/codesourcery/arm-none-linux-gnueabi/libc
        * Build GLIBC libraries
        * Rebuild GCC using newly-built-GLIBC.

    Construct gnu system root
        * Environments
            # this directory will be new gnu system root on Android target.
            # gnu root directory on target device
            export ARCH=arm
            export CROSS_COMPILE=${TARGET}-
            # set PATH
        * Install headers and GLIBC
            - copy cross-compiled glibc, headers etc to $TROOT except for i686 executables and related files
        * Build GNU binutils [binutils-2.18]
            - ./configure --prefix=${PREFIX} --host=${TARGET} --target=${TARGET} --disable-nls
        * Build GCC [gcc-4.2.1]
            - ./configure --prefix=${PREFIX} --build=i686-pc-linux-gnu --target=${TARGET} --host=${TARGET}
                --disable-nls --enable-languages=c
        * Build bash [bash-4.0]
            - ./configure --prefix=${PREFIX} -host=${TARGET} --without-bash-malloc
            - install to $PREFIX/bin. And link $PREFIX/bin/sh to $PREFIX/bin/bash
        * Build gnu make [make-3.82]
            - ./configure --prefix=${PREFIX} -host={TARGET}
        * Build busybox
            - Set cross compiler prefix to 'arm-none-linux-gnueabi-' and make.
            - install to $PREFIX/bin
              (usually commands in busybox are located at /bin)
            - create link to busybox for each command.
        * copy to target device
            - adb push $PREFIX $TGNUROOT
        * link rootfs to gnu system root.
            - ln -s $TGNUROOT/lib /lib
            - ln -s $TGNUROOT/bin /bin

Confirm & Check
    Build Emacs-23.2
        * push Emacs-23.2 source code to target.
        * ./configure --without-xpm --without-jpeg --without-tiff --without-gif --without-png --without-rsvg
             --without-xft --without-libotf --without-m17n-flt --without-toolkit-scroll-bars --without-xaw3d
             --without-xim --without-gpm
        * 'make' should be done without error.

    Running Emacs
        * copy termcap.src from "http://www.opensource.apple.com/source/emacs/emacs-39/emacs/etc/termcap.src".
          And put this /usr/etc/termcap.src.
        * And set following environment variable
        * Emacs should work without error in 'adb shell' terminal.

        * headers and GLIBC built for cross-compiling should be used as they are at target system root.
          (To use cross-compiled binaries on target device without any potential issues.)
        * Some open source packages check only /lib and /usr/lib (/usr/local/lib isn't considered).
          So, fundamental libraries would be better to be installed at /usr/lib,
         even if it's default location is /usr/local/lib

Setting up gnu system root is the first step to construct gnu software stack on the system.
And, now it's done.
So, next step is installing packages to set up development-friendly environment on the Android device.
Below description is summary of issues that I faced against during installing gnu packages.

* Executing /usr/bin/su doesn't run ~/.bashrc
    ~/.bashrc is not executed if user shell is set up as /bin/sh, even if /bin/sh is just symbolic link of /bin/bash.
    Let's assume that /bin/sh -> /bin/bash.
    In this case, executing /bin/sh means "run bash as just 'shell' - sh".
    So, to make ~/.bashrc be run automatically, default shell of user should be set as /bin/bash not /bin/sh

* default .bashrc of normal(ex. ubuntu) desktop PC can be used as a template in Android device.

* terminal editor programs - vi, nano, emacs etc - don't work or work abnormally.
    Environment related with 'Terminal' should be set correctly.
        - Environment variables
            export TERM=xterm
            export TERMINFO=/etc/terminfo
            export TERMCAP=/etc/termcap
    Related files at /etc
            this has setting values for various terminal types - linux, vt100, xterm and so on.
            /etc/terminfo of desktop linux PC can be used as it is.
            this is required by emacs.
            termcap.src(included at termcap source release) can be used as /etc/termcap.

* mode of newly created file becomes 0666 or 0777.
    umask should be set at .bashrc .
        umask 022

* window of editor programs like vi, emacs is default screen size (80x24)
 even if real screen size of terminal emulator is bigger.
    resize command should be executed.
    putting it at .bashrc is recommended.
    this command sets environment variables - COLUMNS and LINES - according to current terminal window size
   and export it.

* various colors are not used at the output of ls command.
    check that dircolors command is installed and this command is set correctly at .bashrc

* sudo command doesn't give any chance to enter password. It only says "Sorry, try again.".
    pam is not correctly binded with sudo.
    install /etc/pam.d/sudo file.
    (sample.pam included at sudo source code release can be a good reference.
     - especially, second option - use pam_unix - is recommended)

* icmp protocol is not recognized by ping - included at inetutils - command.
    check /etc/protocols file is correctly installed.
    this file can be used by copying desktop's one.

* localhost is not recognized even though ip address -  - works well.
    check followings at /etc/hosts    localhost
    check below line at /etc/nsswitch.conf (related with nameserver)
        hosts: files dns

Anything to do?

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[Ubuntu] C-s and C-q doesn't work in gnorm-terminal

Domain/Linux 2011.03.18 06:08
This is due to flow control.
C-s and C-q is reserved key sequence for flow control.
So, by disabling it - just type 'stty -ixon' - you can use C-s and C-q key sequence.
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[Android] NDK issues (found)

Domain/Android 2011.02.15 16:11

* common

+ '-rdynamic' is not supported.
  android dynamic linker allows 'undefined symbol' only for weak symbol.(See (*1))
+ 'tmpfile()' function always returns NULL. "No such file or directory!"
+ 'strtod()' doesn't support '0xXXXX' format.

* NDK 8

'regex.h' exists in 'include'. But function bodies are not in library.

* NDK 9

'pthread_rwlock_xxxx' is declared in 'pthread.h'. But body is missing in library.
'pthread_exit' is declared without 'noreturn' attribute.
'regex' functions doesn't work as it should be. (bug? or not-implemented yet?? I have no idea.)

to be continued...

===== Details =====

(*1) : '-rdynamic' and 'weak' symbol (Updated at 2011-Aug-29)

Here is sample code to for testing 'weak' symbol at Android.

[ main.c ]
#include <dlfcn.h>
#include <stdio.h>

int g_d;

main() {
    void* handle;
    void  (*prf)(void);

    g_d = 369;

    handle = dlopen("/data/libgtst.so", RTLD_LAZY);
    if (!handle) {
        printf("Fail to load library\n");

    prf = dlsym(handle, "print_g");
    if (NULL != dlerror()) {
        printf("Fail to get symbol print_g\n");

    printf("=== DONE! ===\n");

[ lib.c ]
#include <stdio.h>

extern int g_d __attribute__((weak));

print_g(void) {
    printf("==> %d\n", g_d);

[ Android.mk ]
LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_MODULE := libgtst


include $(CLEAR_VARS)

----- Test Steps -----
* build above codes at Android NDK
adb push libgtst.so /data/libgtst.so
adb push test /data/test
adb shell /data/test
==> 369
=== DONE! ===

to be continued...

tags : ndk
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[Ubuntu] visual effect doens't work with Nvidia driver...

Domain/Linux 2011.01.19 11:12

Model : HP EliteBook 8530w
Host : Linux hbg683-laptop 2.6.35-24-generic-pae #42-Ubuntu SMP Thu Dec 2 03:21:31 UTC 2010 i686 GNU/Linux

Current state : 'nvidia-xxx' is installed at 'synaptic package manager'. And then driver is updated by 'NVIDIA-Linux-x86-260.19.12.run' installer.
=> visual effect doesn't work.

Actions done : uninstall all 'nvidia-xxx' packages from 'synaptic package manager'. And then install driver by running 'NVIDIA-Linux-x86-260.19.12.run' installer.
=> Some errors are raised. (something like cannot copy xxx-260.19.06 bla... bla...)

Now visual effect works very well!!

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[Linux] Writing input event directly.

Domain/Linux 2010.11.29 16:03

This is a kind of reminder.
(On Android)

Source code.

    struct input_event;
: write 'struct input_event' to input event node.
    struct input_event ev;
    write(fd, &ev, sizeof(ev));

File system

/dev/input/*, /proc/bus/input/*

Touch event 

   type  code  value
<common> EV_ABS
Press (or Drag)Release EV_KEY
<common>  EV_SYN 0 0

Key event

  type code value
Press EV_KEY <key code> 1
Release EV_KEY <key code> 0

tags : EVENT, input
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