This is the release notes for linux release v0.97 with format adjusted by removing/replacing tabs/spaces/new lines. This notes document can give us an understanding of the early development of the Linux kernel. The original ASCII formatted version is at the end of this post. Changes in 0.97: The VESA-support was removed. I’d be happy to…
This is the release notes for linux release v0.95 (source code: linux-0.95.tar.gz) with format adjusted by removing/replacing tabs/spaces/new lines. This notes document can give us an understanding of the early development of the Linux kernel. The original ASCII formatted version is at the end of this post. RELEASE NOTES FOR LINUX v0.95 Linus Torvalds, March…
This is the release notes for linux release v0.12 (source code: linux-0.12.tar.gz) with format adjusted by removing/replacing tabs/spaces/new lines. This notes document can give us an understanding of the very initial development of the Linux kernel. Also check Notes for linux release 0.01. The original ASCII formatted version is at the end of this post….
This is the notes for linux kernel release 0.01 (source code: linux-0.01.tar.gz) with format adjusted by removing/replacing tabs/spaces/new lines. This notes document can give us an understanding of whether the Linux kernel started with its very first release. The original ASCII formatted version is at the end of this post. Notes for linux release 0.01…
VirtualBox is a nice open source virtual machine software. It works nicely on Linux and is supported by many Linux distros like Ubuntu in their official package repositories, so it is quite easy to set it up on Linux. The VMs can also be managed in command line using the vboxmanage command line tool provided…
It is common that the root disk space is not enough when running a Virtual Machine in the cloud such as Amazon Web Service (AWS). The cloud storage usually provides tools or facilities to enlarge a virtual disk size. However, to make the Linux recognize and and use the enlarged disks without rebooting the OS,…
Sparse files are common in Linux/Unix and are also supported by Windows (e.g. NTFS) and macOSes (e.g. HFS+). Sparse files uses storage efficiently when the files have a lot of holes (contiguous ranges of bytes having the value of zero) by storing only metadata for the holes instead of using real disk blocks. They are…
How to get a server’s serial number remotely? Tested on Linux Ubuntu 14.04 Trusty > sudo apt-get install dmidecode > sudo dmidecode -s system-serial-number I tried this on several Linux boxes with CentOS 7 and it seems A physical node returns a string like System Serial Number. A KVM VM returns a string like 3fd12bba-12d4-48c7-875a-7a5f57ed8a9a….
What is the difference between work conserving I/O scheduler and non-work conserving I/O scheduler? In a work-conserving mode, the scheduler must choose one of the pending requests, if any, to dispatch, even if the pending requests are far away from the current disk head position. The rationale for non-work-conserving schedulers, such as the anticipatory scheduler…
General question for developers to access data between VM and VMM. As I know, paravirtualization solution is a good way to share data for VM and VMM since it has better performance. Please use Virtio 9p solution for QEMU/KVM. Note that you need to load 9p related modules for guest kernel. Add following in your…
In Java, how to get the epoch timestamp, the number of seconds passed since the epoch? In Java, you can get the current time in milliseconds and then calculate the epoch time: long ts = System.currentTimeMillis()/1000; Example: $ wget –quiet https://github.com/albertlatacz/java-repl/releases/download/428/javarepl-428.jar -O /tmp/javarepo-428.jar && java -jar /tmp/javarepo-428.jar Welcome to JavaREPL version 428 (Java HotSpot(TM) 64-Bit…
Any good suggestions on a Java REPL implementation like ‘scala’ and ‘python’ or ‘php -a’? The java-repl tool https://github.com/albertlatacz/java-repl/ works nicely for most situations for me. It is released as a .jar. Hence, it is easy to download and run: $ wget –quiet https://github.com/albertlatacz/java-repl/releases/download/428/javarepl-428.jar -O /tmp/javarepo-428.jar && java -jar /tmp/javarepo-428.jar One usage example is as…
If you install libvirt from ubuntu software library like this sudo apt-get install libvirt-bin The default version is 1.2.2 for Ubuntu Trusty. However, after you upgrade it to version 2.5.0 from its source codes (restart the libvirtd service), you will see following error if you want to install vm with virt-install. # ./installkvm1.sh Starting install……
I update libvirt version and want to start VM with the new libvirt tools but I failed as follows. > sudo virsh start kvm1 error: Failed to start domain kvm1 error: Network not found: no network with matching name ‘default’ It seems that the default ‘virbr0’ is missing after I update libvirt so I solve…
Sometimes, we may want to know the specific benchmark can cause what kind of VM exits. 1, Install perf. 2, # perf kvm stat record -a ^C 3, # perf kvm stat report This will report your VM exit numbers and what kind of operation lead to VM exit. You may need to compare many…
Hello, I have installed Xen4Centos on Centos7, having single NIC card with bridge network and have two VMs on that. In one VM, I want to add two static IP one for webserver and one for mail server. So I have created IP alias in guest VM, it was created but it was not pinging…
How to attach and mount Xen DomU’s disk partitions on Linux without Xen? You can use kpartx to create devices from the VM disk image (say, ./vmdisk0). To activate all the partitions in a raw VM disk image: # kpartx -av ./vmdisk0 This will output lines such as: add map loop1p1 (253:8): 0 497664 linear…
What’s the maximum number of mmap()‘ed ranges that a process can makes and how to set the limits on Linux? I have a program that mmap()s and mprotect()s lots ranges. After allocating many ranges, mprotect() starts to fail with ENOMEM error number. From the man page, ENOMEM means 2 possible problems: ENOMEM Internal kernel structures…
What is the common SSD read/write throughput on common SSDs? Following is a very brief test of the speed of a SSD that I have by hand: # time dd conv=fsync if=/dev/zero of=./test bs=8192 count=1048576 1048576+0 records in 1048576+0 records out 8589934592 bytes (8.6 GB) copied, 20.6098 s, 417 MB/s real 0m21.377s user 0m0.089s sys…
I want to attach a disk to a DomU. The Xen DomU is running and should not be rebooted. Hence, changing its configuration file is not an option. How to dynamically attach a disk to running DomU in Xen? To attach phy:vg_xen/vm-228-large to vm-228 as xvdb, run this on Dom0: # xl block-attach vm-228 phy:vg_xen/vm-228-large…