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Linux Kernel 4.19.70 Release

This post summarizes new features, bugfixes and changes in Linux kernel release 4.19.70. Linux 4.19.70 Release contains 95 changes, patches or new features. In total, there are 101,521 lines of Linux source code changed/added in Linux 4.19.70 release compared to Linux 4.19 release. To view the source code of Linux 4.19.70 kernel release online, please…

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File system Inode flags: difference between FS_IOC_GETFLAGS and FS_IOC_FSGETXATT

What is the difference between FS_IOC_GETFLAGS and FS_IOC_FSGETXATTR ioctl commands? What flags do both return? The comment in fs.h is clear enough to explain itself. In short, FS_IOC_GETFLAGS was for ext2/ext3 only, and FS_IOC_FSGETXATTR is a generic FS level interface. Full comment as follows for your reference (source): /* * Inode flags (FS_IOC_GETFLAGS / FS_IOC_SETFLAGS)…

Getting Epoch Timestamp in C

In C, how to get the epoch timestamp, the number of seconds passed since the epoch? In C, from man 7 time: UNIX systems represent time in seconds since the Epoch, 1970-01-01 00:00:00 +0000 (UTC). A program can determine the calendar time using gettimeofday(2), which returns time (in seconds and microseconds) that have elapsed since…

Max array length in OCaml

What’s the max array length in OCaml. You can check it by: # Sys.max_array_length;; On 64-bit machine: # Sys.max_array_length;; – : int = 18014398509481983 On a 32-bit machne: # Sys.max_array_length;; – : int = 4194303 This is due to the memory representation of arrays. 64 Bit machines are better here. And AFAIK, OCaml was developed…

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A Beginners’ Guide to x86-64 Instruction Encoding

The encoding of x86 and x86-64 instructions is well documented in Intel or AMD’s manuals. However, they are not quite easy for beginners to start with to learn encoding of the x86-64 instructions. In this post, I will give a list of useful manuals for understanding and studying the x86-64 instruction encoding, a brief introduction…

How to Configure Linux Kernel Video Mode for 32-bit and 16-bit Boot Protocols

The Linux kernel has a generic driver for a graphic framebuffer named vesafb on intel boxes. It provides a nice large console for most of modern displays. Setting VESA modes for Linux kernel with 32-bit and 16-bit boot protocol are different. We introduce both methods here. Linux kernel with 32-bit boot protocol For machine with…

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Installing the Flash Plugin for 64-bit Firefox in Linux x86-64

This post introduces how to install flash plugin to 64-bit firefox on a x86-64 Linux (Fedora as the example). Both 64-bit and 32-bit plugin are available. 64-bit flash plugin for Firefox on Linux First, download Flash Player Release for 64-bit Linux from Adobe Labs. Then, unpack the package: $ tar xf flashplayer.tar.gz Check whether all…

Installing and Configuring 32-bit Firefox on 64-bit Linux (Fedora)

On a x86-64 64 bit Linux system, sometimes we may want to use the 32 bit Firefox, although the support to 64 bit Firefox is getting much better. Just for needed ones, this post introduces how to install 32 bit Firefox on 64 bit Linux (Fedora as the example). Install 32-bit firefox First, install firfox.i686…