sync

Author: cirosantilli

README.md

@@ -54,6 +54,7 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
     1.  [blkid](blkid.md)
     1.  [fdisk](fdisk.md)
     1.  [FUSE](FUSE.md)
+    1.  [Forensic rm](forensic-rm.md)
     1.  [fuser](fuser.md)
     1.  [lsblk](lsblk.md)
     1.  [fstab](fstab.md)

alternatives.md

@@ -21,3 +21,7 @@ Strict real time:
 Dedicated OSes / firmware:
 
 - <https://en.wikipedia.org/wiki/Rockbox> , music players
+
+Microcontrollers: seems like Linux requires a MMU:
+
+- <https://en.wikipedia.org/wiki/ΜClinux>

font.md

@@ -95,6 +95,7 @@ TODO what is it.
 
 - <https://www.google.com/fonts> `woff2`.
 - <https://fontlibrary.org/> `otf`
+- <https://www.gnu.org/software/freefont/>
 
 ## Concepts
 

forensic-rm.md

@@ -0,0 +1,28 @@
+# Forensic rm
+
+`rm` only removes files from filesystem indexes, but the data remains in place until the event that another file is written on it, which may take several minutes or hours.
+
+Even after the file data overwritten few times, it is still possible to recover the data using expensive forensic methods (only viable for organizations).
+
+To permanently remove data from hard disk, you must use a tool like shred, which writes certain sequences to the hard disk, making it impossible to recover the data even with forensic methods.
+
+Such operations take a very long time, and are not viable on entire hard disks, so if you serious about clearing a hard disk, mechanical destruction is a better option (open the hard disk case and destroy the disk).
+
+This is specially important for data-centers that are reusing / throwing away data.
+
+- <http://askubuntu.com/questions/57572/how-to-delete-files-in-secure-manner>
+- <http://security.stackexchange.com/questions/5662/is-it-enough-to-only-wipe-a-flash-drive-once/5665#5665>
+- <http://security.stackexchange.com/questions/89404/how-do-i-prevent-ssd-file-recovery>
+
+Tools:
+
+- full-disk encryption
+- `wipe`
+- `shred`
+- `sfill`
+
+Physical methods:
+
+- <http://askubuntu.com/a/58697/52975>
+
+## Recover data removed with rm like tools

gimp.md

@@ -115,6 +115,6 @@ Shortcuts:
 
     - `Ctrl + A + drag`: move the selection elsewhere
 
-    - `Ctrl + Shift + V`: open selection as new image
+    - `Ctrl + Shift + V`: open selection / clipboard as a new image
 
 -   `Ctrl + R`: add new rectangle to existing selection

kdevelop.md

@@ -10,7 +10,7 @@ C / C++ focused, but other languages also supported: <http://developer.kde.org/~
 
 - Vi input mode: Settings > Editing > Vi input mode > Use
 
-## Navigate souce
+## Navigate source
 
 - Import existing source: File > Import > CMake. Done. Just works!
 - Jump to definition: Ctrl + click.

kernel/code-paths/cow.md

@@ -0,0 +1,6 @@
+# COW
+
+<http://stackoverflow.com/questions/37565750/how-did-linux-implements-cow>:
+
+- `/home/ciro/git/linux/src/arch/x86/mm/fault.c:__do_page_fault` x86 page handling
+- major effect: calls the arch agnostic `mm/memory.c:handle_mm_fault`

kernel/source-tree.md

@@ -227,6 +227,8 @@ Sound code.
 
 Memory management.
 
+`mm/memory.c`: centerpiece of memory management
+
 ## IPC
 
 IPC stuff such as semaphores under `sem.c` or message queues under `mqueue.c`.

libreoffice/README.md

@@ -8,6 +8,10 @@ WYSIWYG text editor, tables, image editor, database management.
 
 How to add new spell checking language: <http://askubuntu.com/questions/72099/how-to-install-a-libreoffice-dictionary-spelling-check-thesaurus>
 
+## Write
+
+How to end a list??
+
 ## Calc
 
 Table /spreadsheet editor like Excel.

qemu.md

@@ -175,7 +175,7 @@ QEMU has a specific disk format called *qcow2* which allows for further capabili
 
 Boot from given floppy image.
 
-https://github.com/dcloues/os_tutorial can only be run with it.
+<https://github.com/dcloues/os_tutorial> can only be run with it.
 
 Must be used when `grub.cfg` uses:
 
@@ -269,7 +269,7 @@ Pass kernel boot parameters (command line arguments):
 
     -append "init=/dev/sbin panic=1"
 
-## driver
+## drive
 
 QEMU 2.3.0 complains with a warning if we don't set `format`, so in this version we have to use:
 
@@ -288,3 +288,24 @@ Nope, QEMU is just designed to be fast, and performance is not well documented b
 - <http://stackoverflow.com/questions/17454955/can-you-check-performance-of-a-program-running-with-qemu-simulator>
 - <http://stackoverflow.com/questions/14259542/cycle-accurate-simulation-of-x86-hardware>
 - <https://en.wikipedia.org/wiki/Computer_architecture_simulator>
+
+## GPU
+
+-   <http://stackoverflow.com/questions/5789418/how-do-i-add-a-virtual-gpu-into-qemu>
+    - <http://stackoverflow.com/questions/5762039/create-virtual-hardware-kernel-qemu-for-android-emulator-in-order-to-produce-o/5763466#5763466>
+
+## static
+
+Ubuntu 16.04:
+
+    sudo apt-get intall qemu-user-static
+
+Usermode emulation. E.g., get a Linux ARM statically linked executable on an x86 machine, then you can run it with:
+
+    qemu-arm-static ./executable
+
+QEMU emulates the ISA, and converts system calls to the host arch! Amazing.
+
+`-L` can be used to run with dynamic libraries: <http://stackoverflow.com/questions/16158994/qemu-arm-cant-run-arm-compiled-binary>
+
+    qemu-arm-static -L /usr/arm-linux-gnueabihf ./executable

utils.sh

@@ -657,22 +657,6 @@
 
     # -r: recursive. Mandatory for directories. Potentially dangerous.
 
-  ## recover data removed with rm like tools
-
-    # `rm` only removes files from filesystem indexes, but the data remains in place
-    # until the event that another file is writen on it, which may take severl minutes or hours.
-
-    # Even after the file data overwritten few times, it is still possible to recover
-    # the data using expensive forensic methods (only viable for organizations).
-
-    # To permanently remove data from hard disk, you must use a tool like shred,
-    # which writes certain sequences to the hard disk, making it impossible to
-    # recover the data even with forensic methods.
-
-    # Such operations take a very long time, and are not viable on entire hard disks,
-    # so if you serious about clearing a hard disk, mechanical desctruction is a better option
-    # (open the hard disk case and destroy the disk).
-
   ## rename
 
     # Mass file regex renaming.