Kernel, Virus and Programming

openstack – restart error : Max retries exceeded with url

If you install openstack by devstack, when you reboot your server and restart the openstack by this script http://www.scalegrid.net/blog/?p=52, when you browse to the dashboard and you will see this error message “HTTPConnectionPool(host=’192.168.100.170′, port=8776): Max retries exceeded with url: /v1/b721f5b1f7cd43dd83ee573f6d4e6c74/os-quota-sets/b721f5b1f7cd43dd83ee573f6d4e6c74 (Caused by <class ‘socket.error’>: [Errno 111] Connection refused)” You should check with your endpoints server…
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2013/04/09 0

Openstack architecture diagram (kvm, qemu-kvm, libvirt, nova, cinder)a

Correct me if i am wrong. Openstack components (nova, cinder, glance) controls libvirt to provide visualization and libvirt use qemu-kvm as the hypervisor. The reason openstack don’t control the qemu-kvm directly is because libvirt provides better cross VM functionality (it can adopt to xen, vmware, etc…) and it provides high-end function such pool management and…
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2013/03/29 0

put python+django to apache through virtualhost

to put python+django to apache through virtualhost 1) edit /etc/httpd/conf/httpd.conf 2) edit /root/workspace/MyDjangoProject/P1/wsgi.py, change it to


2013/03/26 0

error in manage.py createsuperuser

error in manage.py createsuperuser To solve the above issues, type in


2013/03/26 0

GDB will remove all breakpoint and set it back repeatly

When you set the breakpoint by input the “b” command, the gdb will not set it immediately, it will wait until the user pressed “c” to cont execute the program. After you pressed “c”, gdb will set all the breakpoints for you. The most funny thing is : when gdb hit a breakpoint and gain…
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2013/03/23 0

qemu debug server hang after breakpoint is hit

If you are developing a debug server for qemu, after qemu hit a breakpoint, your server have to remove the breakpoint manually and re-insert it after the cpu passed that EIP, otherwise the cpu will forever stay in the EIP and can’t single-step/cont to the next instruction. If you take a look the gdbstub.c, gdb…
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2013/03/21 0

QEMU migration via QMP / Monitor command

I just tested the qemu-kvm with QMP, when i send out the qmp command for migration, it takes 20 seconds, it is much slower than type in the command in qemu monitor.


2013/03/21 0

How to use QMP, send command remotely to qemu

To use qmp and send command to qemu from another process, start qemu by This will create a file /tmp/test.gmp for interchange the command. Then you can start another terminal and invoke command.txt: !!! remark, must invoke { “execute”: “qmp_capabilities” } before invoke any qmp command


2013/03/20 1

openstack conflict with virtualbox

When you are running vm in virtual box, and try to start any vm in openstack. The vm that are running in virtualbox will crash immediately, you need to do the follow command to shut it down. If you want to restart that VM, please rmmod the kvm module. I guess is that the kvm…
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2013/03/17 0

OOM has trouble to KVM, it can’t shot down the kvm

In Linux, if the system is out of memory, OOM will pick one process to kill. But someone reported the OOM can’t kill the qemu-kvm, that mean if you are running many VMs that eat up all the memory, the Linux will hang because OOM can’t kill them In tried to run 64 VMs using…
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2013/03/17 0

Restructuring the debugger

At the moment, i am facing 2 big problems of bochs, the first one is unsolvable, bochs running too slow. It is ok if you are doing a hobby OS development, but if you are trying to use bochs to run a full feature Linux kernel or a windows 7, it is just so slow.…
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2013/03/13 0

qemu single step will fail if current EIP hit a breakpoint

I use the following code to insert a breakpoint in physical address 0x1600000 qemu successfully hit the breakpoint and stop, then i try to single-step by the following code: Nothing happened, the EIP still stay in 0x1600000, but if i delete the breakpoint, the single step just work again. Am I missed something?


2013/02/14 0

when you debugging qemu, it will keep firing SIGUSR1 so gdb will always catched in some breakpooints that are not defined by you

when you debugging qemu, it will keep firing SIGUSR1 so gdb will always catched in some breakpooints that are not defined by you, to turn off the SIGUSR1, you have to: (gdb) info signal SIGUSR1 Signal Stop Print Pass to program Description SIGUSR1 Yes Yes Yes User defined signal 1 And if deemed to not…
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2013/02/12 0

linker script offset seems crazy

linker script offset seems crazy, take a look the following two pictures  


2013/02/09 0

compile grub2 : error: ‘gets’ undeclared here

if you compile grub2 , you may get “error: ‘gets’ undeclared here yum”, to fix it, run the following command: sed -i -e ‘/gets is a security/d’ grub-core/gnulib/stdio.in.h  


2013/02/09 0

compile 64 bits newlib on 64 bits linux host

If you compile newlib in x86-64 host and want to have 64-bits newlib, you have to add “–disable-multilib“, otherwise you will get the following error:


2013/02/03 0

PSI probe for tomcat can’t generate chart

Add this “CATALINA_OPTS=-Djava.awt.headless=true” to catalina.sh


2013/01/31 0

newlib compile error in Fedora 18 64 bits

when you meet the following error, add “.code32” can fix it. ../../../../../../newlib-1.19.0/newlib/libc/machine/i386/memcmp.S: Assembler messages: ../../../../../../newlib-1.19.0/newlib/libc/machine/i386/memcmp.S:18: Error: invalid instruction suffix for `push’ ../../../../../../newlib-1.19.0/newlib/libc/machine/i386/memcmp.S:21: Error: invalid instruction suffix for `push’ ../../../../../../newlib-1.19.0/newlib/libc/machine/i386/memcmp.S:22: Error: invalid instruction suffix for `push’ ../../../../../../newlib-1.19.0/newlib/libc/machine/i386/memcmp.S:23: Error: invalid instruction suffix for `push’ ../../../../../../newlib-1.19.0/newlib/libc/machine/i386/memcmp.S:72: Error: invalid instruction suffix for `pop’ ../../../../../../newlib-1.19.0/newlib/libc/machine/i386/memcmp.S:73: Error: invalid instruction suffix for…
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2013/01/30 0

10 places where anyone can learn to code

Teens, tweens and kids are often referred to as “digital natives.” Having grown up with the Internet, smartphones and tablets, they’re often extraordinarily adept at interacting with digital technology. But Mitch Resnick, who spoke at TEDxBeaconStreet in November, is skeptical of this descriptor. Sure, young people can text and chat and play games, he says, “but that…
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2013/01/30 1