Kernel debug with kgtp on android

November 1st, 2011 BianJiang No comments

KGTP is a realtime and lightweight Linux Kernel GDB debugger and tracer. It makes Linux Kernel supply a GDB remote debug interface. Then GDB in current machine or remote machine can debug and trace Linux through GDB tracepoint without stopping the Linux Kernel. And even if the board doesn’t have GDB on it and doesn’t have interface for remote debug. It can debug the Linux Kernel using offline debug. Now, it supports X86-32, X86-64, MIPS and ARM.

This article describes how to use kgtp debug linux kernel on android.

Kernel Building

 General setup  --->
     [ * ] Prompt for development and/or incomplete code/drivers
     [ * ] Kprobe
Kernel hacking  --->
     [ * ] Compile the kernel with debug info
     [ * ] Compile the kernel with frame pointers

Building KGTP

Config KGTP Makefile

KERNELDIR := /work/vc1000/src/kernel-vc1000-2.3
ARCH=arm
CROSS_COMPILE=/usr/local/arm/arm-2009q3/bin/arm-none-linux-gnueabi-

error: ‘GTP_VAR_RDTSC_ID’ undeclared(latest version fixed By: teawater )

  CC [M]  /home/border/work/kernel/kgtp/trunk/gtp.o
/home/border/work/kernel/kgtp/trunk/gtp.c: In function 'gtp_gdbrsp_qtv':
/home/border/work/kernel/kgtp/trunk/gtp.c:6318: error: 'GTP_VAR_RDTSC_ID' undeclared (first use in this function)
/home/border/work/kernel/kgtp/trunk/gtp.c:6318: error: (Each undeclared identifier is reported only once
/home/border/work/kernel/kgtp/trunk/gtp.c:6318: error: for each function it appears in.)
/home/border/work/kernel/kgtp/trunk/gtp.c:6320: error: implicit declaration of function 'rdtscll'

* solution:

diff --git a/trunk/gtp.c b/trunk/gtp.c
index 4d0c9a2..75c145e 100644
--- a/trunk/gtp.c
+++ b/trunk/gtp.c
@@ -6315,11 +6315,13 @@ gtp_gdbrsp_qtv(char *pkg)
                if (num == GTP_VAR_CLOCK_ID) {
                        val = (uint64_t)GTP_LOCAL_CLOCK;
                        goto output_value;
+#ifdef CONFIG_X86
                } else if (num == GTP_VAR_RDTSC_ID) {
                        unsigned long long a;
                        rdtscll(a);
                        val = (uint64_t)a;
                        goto output_value;
+#endif
                } else if (num == GTP_VAR_XTIME_SEC_ID
                           || num == GTP_VAR_XTIME_NSEC_ID) {
                        struct timespec time

Complie and Install KGTP

make
sudo su
adb push gtp.ko /system/vendor/lib
exit

KGTP Running On Android

#Open the KGTP interface in current machine.
su
cd /system/vendor/lib
insmod gtp.ko
lsmod
nc -l -p 1234 < /sys/kernel/debug/gtp > /sys/kernel/debug/gtp

Host PC

cd /work/vc1000/src/kernel-vc1000-2.3
make -j8

Network connect to gtp

# symbian use "set gnutarget elf32-littlearm-symbian"
# vxworks use "set gnutarget elf32-littlearm-vxworks"
gdb-release -ex "set gnutarget elf32-littlearm" -ex "file ./vmlinux"

# if you want see the debug info
(gdb) set debug remote 1

# connection your remote device
(gdb) target remote 192.168.2.213:1234

USB connect to gtp

sudo su
# forward socket(adb forward <local> <remote>)
adb forward tcp:1234 tcp:1234
exit
gdb-release -ex "set gnutarget elf32-littlearm" -ex "file ./vmlinux"
# connection your remote device
(gdb) target remote 127.0.0.1:1234

Debugging with gtp

(gdb) trace vfs_readdir
Tracepoint 1 at 0xc02289f0: file /build/buildd/linux-2.6.35/fs/readdir.c, line 23.
(gdb) actions
Enter actions for tracepoint 1, one per line.
End with a line saying just "end".
>collect $reg
>end
(gdb) tstart

Change To Android Device Shell And Run ls Command * Android Device

$ ls

Back To Host PC GDB Shell * Host PC

(gdb) shell ls
vmlinux-2.6.35-30-generic
(gdb) tstop
(gdb) tfind
Found trace frame 0, tracepoint 1
#0  vfs_readdir (file=0x0, filler=0x163d8ae3, buf=0x18c0) at /build/buildd/linux-2.6.35/fs/readdir.c:23
23      {

Good luck, Happy Hacking…

Very grateful for teawater

References

* kgtp Linux Kernel GDB Tracepoint module

* kgtp Quick start

* kgtp How to

* How To Use KGTP In Android

* GDB Tracepoints

Categories: Android, Kernel, Tech.Notes Tags: android, gdb, Kernel, kgtp, tracepoints

AOSP source code back online

October 21st, 2011 BianJiang No comments

Hi!

As you know, like many other projects the Android Open-Source Project was affected by the recent kernel.org downtime. So, we’re pleased to let you know that the Gingerbread source code is now available again, and AOSP git servers are back online.

Even before the kernel.org downtime, it was clear that AOSP was sometimes taxing kernel.org’s git infrastructure. When we did the Gingerbread source release, for example, load due to AOSP made part of kernel.org unusable for several days. This isn’t fair to kernel.org’s staff or the community, so for some time we’ve been preparing our own git hosting on Google servers.

We were finishing up just as kernel.org experienced their downtime, so the Gingerbread source is now available on Google’s servers. Accordingly, the git URLs have changed.

Here are the instructions to access the new git servers:

You need to get the latest version of the repo tool:
curl https://dl-ssl.google.com/dl/googlesource/git-repo/repo > ~/bin/repo
You need to initialize a new repository:
repo init -u https://android.googlesource.com/platform/manifest -b android-2.3.7_r1
The full instructions are at http://source.android.com/source/downloading.html

There are a few limitations to be aware of:

Our priority has been getting the main source code mirrors back online, so for the moment gitweb source browsing and Gerrit Code Review are still unavailable.
We are now working on bringing AOSP’s Gerrit Code Review site back up, and hope to be able to say something here soon.
It might be a little while longer before gitweb comes back, unfortunately, since Gerrit Code Review is the next priority.
To reiterate, these servers contain only the ‘gingerbread’ and ‘master’ branches from the old AOSP servers. We plan to release the source for the recently-announced Ice Cream Sandwich soon, once it’s available on devices.
As these new servers are, well, new, there may be hiccups if we encounter unexpected issues. However we’re keeping a close eye on them and will respond to any issues as quickly as possible.

Finally, we’d like to send a huge “thank-you” to the kernel.org community and Oregon State University Open-Source Lab staff. They’ve done an incredible job hosting the AOSP source code mirror and Gerrit Code Review for nearly 3 years. Without them, it’s safe to say that AOSP would not be where we are today.

Thanks, and happy coding!

- Dan

From: https://groups.google.com/forum/#!msg/android-building/IwlEJtE1LsI/WtHcsPkUPMcJ

– EOF –

Categories: Android, Kernel, OpenSource Tags: android, Git, Google, Kernel, opensource

libusb must be mounted usbfs

July 20th, 2011 BianJiang 2 comments

今天通过libusb访问一个HID的设备，一调用USBDEVFS_{CLAIMINTERFACE} ioctl就返回-1设备忙, 找了一下午原因也没有找到，快到下班的时候，发现了一篇文章Porting Libusb for Android on the Beagleboard in 5 steps 提到需要把设备加载到usbfs上，结果加载了usbfs设备就能正常访问了。

在网上搜了一圈，发现libusb就是通过usbfs或usbdevfs来链接USB设备，所以在使用之前必须加载usbfs到/dev/bus/usb或/proc/bus/usb目录. 原文如下:

libusb uses a pseudo-filesystem known as ‘usbdevfs` or ‘usbfs` to access
the USB devices connected to your machine. This filesystem must be mounted
under /proc/bus/usb for libusb to work.

libusb移植到Android具体可以参考Porting Libusb for Android on the Beagleboard in 5 steps

需要注意的是:

在命令行加载sysfs需要执行:
- mount -t usbfs -o devmode=666 none /proc/bus/usb
在init.rc中需要使用:
- mount usbfs none /proc/bus/usb -o devmode=0666

参考

Categories: Android, Kernel, Tech.Notes Tags: android, hid, ioctl, mount, usb, usbfs

修改Linux Kernel启动画面

June 3rd, 2011 BianJiang No comments

linux kernel的启动logo存放于KERNEL_PATH/drivers/video/logo/logo_linux_cult224.ppm

是被编译到内核的，所以不能简单的替换就改变原有的logo，按以下命令制作logo_linux_cult224.ppm:


pngtopnm logo.png > logo_linux_cult224.pnm　　　　　　　/*格式转换*/
pnmquant 224 logo_linux_cult224.pnm > logo_linux_cult224.pnm　/*将图像改为224色*/
pnmtopnm logo_linux_cult224.pnm > logo_linux_cult224.ppm　/*将图像转存为ppm格式*/

替换新内核中原有的logo_linux_cult224.ppm，注意备份原有的企鹅logo_linux_cult224.ppm。

内核编译后，且以framebuffer方式启动新内核，此时企鹅图标就变成了自定义的LOGO（注意LOGO图像的尺寸不能大于framebuffer的尺寸）

但是在启动中，logo上会有光标在闪烁，如果需要将光标去除（提示console的光标也会消失），将内核中的KERNEL_PATH/drivers/video/console/fbcon.c中的fb_flashcursor和fbcon_sursor函数体置空。重新编译安装内核即可。

参考: http://www.cnblogs.com/semo/archive/2011/01/05/1926295.html

–EOF–

Categories: Kernel, Tech.Notes Tags: Kernel, Linux, Logo, pngtopnm, pnmquant, pnmtopnm

Pthread创建线程后必须使用join或detach释放线程资源

December 26th, 2009 BianJiang No comments

这两天在看Pthread 资料的时候，无意中看到这样一句话(man pthread_detach):

Either pthread_join(3) or pthread_detach() should be called for each thread
       that an application creates, so that system resources for the thread can be
       released.  (But note that the resources of all threads are freed when the
       process terminates.)

也就是说：每个进程创建以后都应该调用pthread_join 或 pthread_detach 函数，只有这样在线程结束的时候资源(线程的描述信息和stack)才能被释放.

之后又查了pthread_join 但是没有明确说明必须调用pthread_join 或 pthread_detach.

但是再查了 Pthread for win32 pthread_join

When a joinable thread terminates, its memory resources (thread descriptor and stack) are not deallocated until another thread performs pthread_join on it. Therefore, pthread_join must be called once for each joinable thread created to avoid memory leaks.

才知道如果在新线程里面没有调用pthread_join 或 pthread_detach会导致内存泄漏, 如果你创建的线程越多，你的内存利用率就会越高, 直到你再无法创建线程，最终只能结束进程。

解决方法有三个:

1. 线程里面调用 pthread_detach(pthread_self()) 这个方法最简单

2. 在创建线程的设置PTHREAD_CREATE_DETACHED属性

3. 创建线程后用 pthread_join() 一直等待子线程结束。

下面是几个简单的例子

1. 调用 pthread_detach(pthread_self())

#include <stdio.h>

#include <stdlib.h>

#include <pthread.h>

void *PrintHello(void)

{

pthread_detach(pthread_self());

int stack[1024 * 20] = {0,};

//sleep(1);

long tid = 0;

//printf(“Hello World! It’s me, thread #%ld!\n”, tid);

//pthread_exit(NULL);

}

int main (int argc, char *argv[])

{

pthread_t pid;

int rc;

long t;

while (1) {

printf(“In main: creating thread %ld\n”, t);

rc = pthread_create(&pid, NULL, PrintHello, NULL);

if (rc){

printf(“ERROR; return code from pthread_create() is %d\n”, rc);

//exit(-1);

}

sleep(1);

}

printf(” \n— main End —- \n”);

pthread_exit(NULL);

}

2. 在创建线程的设置PTHREAD_CREATE_DETACHED属性

#include <stdio.h>

#include <stdlib.h>

#include <pthread.h>

void *PrintHello(void)

{

int stack[1024 * 20] = {0,};

//pthread_exit(NULL);

//pthread_detach(pthread_self());

}

int main (int argc, char *argv[])

{

pthread_t pid;

int rc;

long t;

while (1) {

printf(“In main: creating thread %ld\n”, t);

pthread_attr_t attr;

pthread_t thread;

pthread_attr_init (&attr);

pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);

rc = pthread_create(&pid, &attr, PrintHello, NULL);

pthread_attr_destroy (&attr);

if (rc){

printf(“ERROR; return code from pthread_create() is %d\n”, rc);

//exit(-1);

}

sleep(1);

}

printf(” \n— main End —- \n”);

pthread_exit(NULL);

}

3. 创建线程后用 pthread_join() 一直等待子线程结束。

#include <stdio.h>

#include <stdlib.h>

#include <pthread.h>

void *PrintHello(void)

{

int stack[1024 * 20] = {0,};

//sleep(1);

long tid = 0;

//pthread_exit(NULL);

//pthread_detach(pthread_self());

}

int main (int argc, char *argv[])

{

pthread_t pid;

int rc;

long t;

while (1) {

printf(“In main: creating thread %ld\n”, t);

rc = pthread_create(&pid, NULL, PrintHello, NULL);

if (rc){

printf(“ERROR; return code from pthread_create() is %d\n”, rc);

//exit(-1);

}

pthread_join(pid, NULL);

sleep(1);

}

printf(” \n— main End —- \n”);

pthread_exit(NULL);

}

测试代码下载

参考: 1. http://www.cnblogs.com/bits/archive/2009/12/04/no_join_or_detach_memory_leak.html

2. Linux 多线程应用中如何编写安全的信号处理函数 http://www.ibm.com/developerworks/cn/linux/l-cn-signalsec/index.html?ca=drs-cn-0618

3. man pthread_detach http://www.kernel.org/doc/man-pages/online/pages/man3/pthread_detach.3.html

4. man pthread_join http://www.kernel.org/doc/man-pages/online/pages/man3/pthread_join.3.html
–
Bian Jiang
Blog: http://www.wifihack.net/

Categories: Kernel, Tech.Notes Tags: detach, join, Linux, pthread, thread

Newer Entries Older Entries

Linux kernel, Android, Golang & Recsys

Archive

Kernel debug with kgtp on android

Kernel Building

Building KGTP

Config KGTP Makefile

error: ‘GTP_VAR_RDTSC_ID’ undeclared(latest version fixed By: teawater )

Complie and Install KGTP

KGTP Running On Android

Host PC

Network connect to gtp

USB connect to gtp

Debugging with gtp

Good luck, Happy Hacking…

Very grateful for teawater

References

AOSP source code back online

libusb must be mounted usbfs

修改Linux Kernel启动画面

Pthread创建线程后必须使用join或detach释放线程资源

站内搜索

Go语言中文讨论组

Sponsored Links

Categories

Recent Posts

Meta

Pages

Recent Comments

Categories

Blogroll

Archives