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6

Overwriting swap with random values is equivalent to overwriting process images in memory with random values. If a text segment with random values is executed, the most likely result is process termination due to an illegal instruction (signal SIGILL). If a data segment with random values is read, the result is most likely process termination due to a ...


4

If you just mean running "swapoff -a" when you say "clean up", then no. If you corrupt/overwrite the swap device/file, an application that gets swapped back in (with corrupted data) is very likely to crash, yes. The kernel does not get swapped out, so the "system" would not crash.


3

A disk should grant that a sector is written atomically. The sector size was 512 bytes and today is typically 4096 bytes for larger disks. In order to get no problem from partially written "blocks", it is important to write everything in a special order. Note that the only reason why there could be a partially written part in the filesystem is a power ...


2

The kernel on OpenBSD via in6_ifattach_linklocal, as found by a fgrep -rl fe80 /usr/src 2>/dev/null search.


2

The Unix/Linux system offers the POSIX system calls open(2)/close(2)/read(2)/write(2) and stat(2) and some higher-level functions like opendir(3)/closedir(3)/readdir(3), which are enough to write the tools stated (it is easier using the C wrappers). Part of the hard job of the kernel is precisely to make them work on the various filesystems offered, and make ...


2

This is potentially related to El Capitan and its System Integrity Protection (csrutil status) which can affect the dtrace behaviour. The potential fix includes rebooting Mac into recovery mode (⌘-R at boot time), then in Terminal run: csrutil enable --without dtrace to keep SIP enabled, but disable DTrace restrictions (note: this is undocumented ...


1

For most tools, the underlying layer is the C Standard Library ("libc"). libc provides a number of low-level file handling routines, such as open, read, and write. These routines in turn interface to the filesystem layer in the kernel, which sits on top of the kernel's block device layer, the device drivers, and finally the hardware. One implementation of ...


1

I'm looking at this one: Slurm is an open-source workload manager designed for Linux clusters of all sizes. It provides three key functions. First it allocates exclusive and/or non-exclusive access to resources (computer nodes) to users for some duration of time so they can perform work. Second, it provides a framework for starting, executing, and ...


1

Adding more detail to the answers above. As we're using VM's more and more, a linux host may be a vm on one of these cloud environments. In both examples 1 & 2 we've got a good idea of the applications running and so how much RAM they consume. In 3, not so much Example 1 A high performance private cloud (think the sort most banks would pay millions ...


1

You can manipulate some of the pci bus registers of the device fairly easily with setpci. Note: this is dangerous and may crash your system! For example, find the pci bus and slot for your graphics board: $ lspci | grep VGA 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) $ ...


1

Some notes, mainly on BIOS/GRUB systems. BIOS system with GRUB: BIOS start of from address 0xfffffff0 (x86). Do various tests e.g. POST. If all well then check the devices, in the order configured and saved in CMOS. First boot device that has a valid MBR, (signature at offset 510 is 0x55aa), is loaded into memory at address 0x7c00. Then BIOS leaves ...


1

On any POSIX system, the interface between applications and the kernel is a few function calls: open, read, write, close, etc. An application such as cat calls those functions; it doesn't care how the functions are implemented under the hood. On Unix systems, those functions are actually system calls: the application calls the kernel. Inside the kernel, a ...


1

"redirection" is a concept of the shell, and the details around it depend on which shell you are talking about. Though, one might say that the basis for redirection rests with the notion that programs have pre-opened input and output file descriptors when they start, which traces back to how the execve function works. Namely that the child process inherits ...


1

For redirection, I would assume this (redirection) is implemented by the shell replacing stdin (by input for < input) and stdout (by output for > output) using dup2() - open files for input and output in = open() out = open() dup2(in, 0) // replace input file with stdin dup2(out, 1) // replace output file with stdout close(in) ...


1

You can also temporarily blacklist them on the grub command line (linux line) when you boot with the syntax module_to_blacklist.blacklist=yes OR modprobe.blacklist=module_to_blacklist You need to modify the grub,cfg to make the changes permanent. Mind you, this solution will not work for few modules


1

That depends on the underlying storage technology. Some storage allows a certain block size to be stored atomically, typically a power of 2 which is at least 256 and usually in the 1kB—4kB range. If that's the case, then the filesystem layer can replace blocks in place, provided that the replacement of the block yields a valid system state. This is fine ...


1

The linux kernel source in Ubuntu is open source, so there is no problem with using (parts of) it, just like you can use any other linux kernel source. Using the Ubuntu name for your OS is not allowed unless you have permission from Canonical (who own the Ubuntu trademark), which in general is true for any other trademarks and their owners too. Of course ...



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