bak

Author: cirosantilli

README.md

@@ -291,6 +291,7 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
     1. [Xen](xen.md)
     1. [Vagrant](vagrang/)
     1. [Intel SDE](intel-sde.md)
+    1. [gem5](gem5.md)
 1.  [Configuration automation](config-automation.md)
     1. [chef](chef/)
     1. [puppet](puppet.md)

chat.sh

@@ -55,6 +55,8 @@
     #go to tty3
     #your message is there!
 
+  # SSH sessions also see those messages.
+
 ## talk
 
   # Commandline chat program.

cloc.md

@@ -51,3 +51,26 @@ Sample output for GDB:
     -------------------------------------------------------------------------------
 
 In 2015 takes around 30 minutes on the Linux kernel: <http://www.quora.com/How-many-lines-of-code-are-in-the-Linux-kernel>
+
+## Per top-level directory breakdown
+
+E.g. for C and C++ only:
+
+    for d in $(git ls-tree HEAD . | awk -F '[[:space:]]' '$2=="tree" {print $4}'); do
+        echo "## $d"
+        cloc --list-file=<(git ls-files "$d" | grep -Fxvf <(git submodule status | cut -d' ' -f3))
+        echo
+    done |& tee /tmp/a
+    cat /tmp/a | awk -F' ' '/^##/{ printf("%-16s %d\n", name, sum); name = $2; sum = 0} /^(C |C\+\+ )/{ sum += $5 }' | tail -n+2 | sort -nrk 2,2
+
+## For each file
+
+    cloc --by-file .
+
+You can then do your own processing.
+
+## gitignore
+
+<https://github.com/AlDanial/cloc/issues/49>
+
+    --vcs=git

dmesg.md

@@ -10,18 +10,72 @@ TODO what kernel function puts messages there?
 
 The messages that appear on the screen at startup are shown there as well. But there are messages which only `dmsg` shows. TODO what is the difference?
 
+Also clear the ring buffer:
+
+    sudo dmesg -c
+
+Good option, so that next time you run:
+
+    sudo dmesg -c
+
+you know that all messages are new.
+
 ## /var/log/dmesg
 
+<http://unix.stackexchange.com/questions/191560/difference-between-output-of-dmesg-and-content-of-var-log-dmesg>
+
+When the kernel finishes booting, it dumps the ring buffer to this file.
+
 The messages are found in `/var/log/dmesg` and rotated log files `dmesg.N.gz`.
 
-TODO: rotated log files contain similar content to the `dmesg`. Where is the content od `dmesg` coming from?
+After boot, further messages are written to the ring buffer, and `dmesg` will see them, but they are not written to `/var/log/dmesg`.
+
+At that point, there seem to be
+
+### /var/log/dmesg.0
+
+`dmesg` from last boot.
 
 ## /proc/kmsg
 
 ## kmsg
 
-TODO when I: `sudo cat /proc/kmsg` it is empty and hangs. Why?
+Looks like a live ring-buffer.
+
+Try:
+
+    sudo cat /proc/kmsg
+
+and then connect and disconnect something like a USB cable.
 
 ## /var/log/boot.log
 
-TODO what kernel function puts messages there?
+TODO what kernel function puts messages there? Looks like service startup / teardown, so possibly upstart?
+
+## /var/log/kern.log
+
+Large log of multiple previous ring buffers.
+
+Set under `/etc/rsyslog.d/50-default.conf`.
+
+## /var/log/messages
+
+Not present in Ubuntu 16.04.
+
+<http://unix.stackexchange.com/questions/35851/whats-the-difference-of-dmesg-output-and-var-log-messages>
+
+## klogd
+
+TODO. Daemon that polls the kernel log: <http://unix.stackexchange.com/a/35853/32558> ?
+
+## syslogd
+
+## /var/log/sysloc
+
+TODO. Daemon that polls the kernel log: <http://unix.stackexchange.com/a/35853/32558> ?
+
+<http://askubuntu.com/questions/26237/difference-between-var-log-messages-var-log-syslog-and-var-log-kern-log>
+
+## rsyslog
+
+<http://www.rsyslog.com/>

gem5.md

@@ -0,0 +1,58 @@
+# gem5
+
+BSD license.
+
+Almost all 2016 commits by ARM and AMD employees.
+
+Started in 2003 by <http://umich.edu/>.
+
+ARM commits start 2009.
+
+AMD commits start 2008.
+
+## Getting started
+
+Build:
+
+    sudo apt-get install mercurial
+    git clone
+    hg clone http://repo.gem5.org/gem5
+    cd gem5
+    hg co stable_2015_09_03
+    scons -j$(nproc) build/ARM/gem5.opt
+
+Run Syscall Emulation (SE) mode:
+
+    build/ARM/gem5.opt configs/example/se.py -c tests/test-progs/hello/bin/arm/linux/hello
+
+Run Full System (FS) mode:
+
+    export M5_PATH='/dist/m5/system'
+    sudo mkdir -p "$PATH"
+    sudo chmod -R 777 "$PATH"
+    cd "$PATH"
+    wget http://www.gem5.org/dist/current/arm/aarch-system-2014-10.tar.xz
+    unxz aarch-system-2014-10.tar.xz
+    tar xvf aarch-system-2014-10.tar
+
+    cd "$GEM_DIR"
+    build/ARM/gem5.opt -d /tmp/output configs/example/fs.py
+
+    # Another terminal.
+    telnet localhost 3456
+
+TODO: which image was used? How to change the default?
+
+    build/ARM/gem5.opt -d /tmp/output configs/example/fs.py --disk-image /dist/m5/system/disks/aarch64-ubuntu-trusty-headless.img
+
+Fails with:
+
+    2777728592500: system.cpu.break_event: break event panic triggered
+
+Some help at:
+
+    build/ARM/gem5.opt -d /tmp/output configs/example/fs.py -h
+
+TODO how were those images generated?
+
+TODO screen / display image?

init.md

@@ -129,10 +129,6 @@ Set the `<start><stop>` levels of the script script:
 
 The above sets start to `2` and stop to `1`.
 
-## init directory
-
-`/etc/init` is Upstart specific. It contains scripts that correspond to Upstart services.
-
 ## upstart
 
 Intended as a backwards compatible replacement for System V.

minimal-distros.md

@@ -55,3 +55,11 @@ Seemed popular, but died in 2008?
 Tiny core Linux: <http://tinycorelinux.net/>, source: <http://git.tinycorelinux.net/index.cgi> Minimalistic with X.
 
 Minimalistic, text based, security: <http://rlsd2.dimakrasner.com/>
+
+## AEL
+
+ARM Embedded Linux.
+
+Linaro ARM board bring-up helper.
+
+<http://www.linaro.org/blog/community-blog/is-linaro-a-distribution/>

nfs.md

@@ -13,3 +13,13 @@ Usage:
     ls /mnt/local
 
 The server may restrict access to only certain paths.
+
+## Server
+
+Good tutorial: <https://www.digitalocean.com/community/tutorials/how-to-set-up-an-nfs-mount-on-ubuntu-14-04>
+
+    sudo mkdir /var/nfs
+    sudo chown nobody:nogroup /var/nfs
+    sudo service nfs-kernel-server start
+    echo '/shared/dir *(rw,sync,no_subtree_check)' | sudo tee /etc/exports
+    sudo exportfs -a

scons/.gitignore

@@ -0,0 +1,3 @@
+*.log
+*.o
+*.out

scons/README.md

@@ -0,0 +1,8 @@
+# SCons
+
+Tested on SCons v2.3.0.
+
+1. [Hello](hello/)
+1. [Define](define/)
+1. [CLI arguments](cli_args/)
+1. [CFLAGS](cflags/)

scons/cflags/.sconsign.dblite

@@ -0,0 +1,7 @@
+Pass compiler flags.
+
+Comments on type:
+
+    //
+
+are only legal in C99+, so C89 should fail on those.

scons/cflags/README.md

@@ -0,0 +1,5 @@
+env = Environment()
+std = ARGUMENTS.get('std', 'c99')
+env.Append(CCFLAGS = '-std=' + std)
+env.Append(CCFLAGS = '-Werror')
+env.Program(target = 'main.out', source = ['main.c'])

scons/cflags/SConstruct

@@ -0,0 +1,4 @@
+int main(void) {
+	// C99
+	return 0;
+}

scons/cflags/main.c

@@ -0,0 +1,2 @@
+#!/usr/bin/env bash
+find . \( -name '*.log' -o -name '*.o' -o -name '*.out' \) -delete

scons/clean

@@ -0,0 +1 @@
+Command line arguments passed to SCons.

scons/cli_args/.sconsign.dblite

@@ -0,0 +1,4 @@
+env = Environment()
+x = ARGUMENTS.get('x', '0')
+env.Append(CPPDEFINES=['X=' + x])
+env.Program(target = 'main.out', source = ['main.c'])

scons/cli_args/README.md

@@ -0,0 +1,5 @@
+#include <stdio.h>
+
+int main(void) {
+	printf("%d\n", X);
+}

scons/cli_args/SConstruct

@@ -0,0 +1 @@
+Preprocessor define.

scons/cli_args/main.c

@@ -0,0 +1,3 @@
+env = Environment()
+env.Append(CPPDEFINES=['X=1'])
+env.Program(target = 'main.out', source = ['main.c'])

scons/define/.sconsign.dblite

@@ -0,0 +1,5 @@
+#include <stdio.h>
+
+int main(void) {
+	printf("%d\n", X);
+}

scons/define/README.md

@@ -0,0 +1 @@
+Hello world.

scons/define/SConstruct

@@ -0,0 +1,2 @@
+env = Environment()
+env.Program(target = 'main.out', source = ['main.c'])

scons/define/main.c

@@ -0,0 +1,5 @@
+#include <stdio.h>
+
+int main(void) {
+	puts("hello");
+}

scons/hello/.sconsign.dblite

@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+
+assert_fail() {
+  echo "Test failed: ${1}"
+  exit 1
+}
+
+top="$(pwd)"
+log_path="${top}/test.log"
+
+./clean
+
+cd "$top"
+cd 'hello'
+scons >>"$log_path" 2>&1
+[ "$(./main.out)" = 'hello' ] || assert_fail 'hello'
+
+cd "$top"
+cd 'define'
+scons >>"$log_path" 2>&1
+[ "$(./main.out)" = '1' ] || assert_fail 'define'
+
+cd "$top"
+cd 'cli_args'
+scons >>"$log_path" 2>&1
+[ "$(./main.out)" = '0' ] || assert_fail 'cli_args 0'
+scons x=1 >>"$log_path" 2>&1
+[ "$(./main.out)" = '1' ] || assert_fail 'cli_args 1'
+
+cd "$top"
+cd 'cflags'
+scons >>"$log_path" 2>&1
+[ scons std=c89 >>"$log_path" 2>&1 ] && assert_fail 'cflags c89'
+
+echo 'All tests passed'