deploy: d086ca4c6179628546796e60bfade25be061f045

1 files changed, 118 insertions, 47 deletions

diff --git a/print.html b/print.html
index 434ecf2..4aadb02 100644
--- a/print.html
+++ b/print.html
@@ -1060,6 +1060,11 @@ For floats one can use <code>%N.Mf</code>, <code>N</code> is the total number in
 <code>M</code>.</p>
 </li>
 <li>
+<p><code>sprintf(&quot;fmt&quot;, expr, ...)</code></p>
+<p>Format the expressions according to the format string. Similar as <code>printf</code>,
+but this is a function and return value can be assigned to a variable.</p>
+</li>
+<li>
 <p><code>strftime(&quot;fmt&quot;)</code></p>
 <p>Print time stamp formatted by <code>fmt</code>.</p>
 <ul>
@@ -1083,7 +1088,7 @@ prints the whole record.</p>
 <h3><a class="header" href="#access-last-fields-in-records" id="access-last-fields-in-records">Access last fields in records</a></h3>
 <pre><code class="language-bash">echo 'a b c d e f' | awk '{ print $NF $(NF-1) }'
 </code></pre>
-<p>Access last fields with arithmetic on the <code>NR</code> number of fields variable.</p>
+<p>Access last fields with arithmetic on the <code>NF</code> number of fields variable.</p>
 <h3><a class="header" href="#capture-in-variables" id="capture-in-variables">Capture in variables</a></h3>
 <pre><code class="language-bash"># /proc/&lt;pid&gt;/status
 #   Name:    cat
@@ -1671,44 +1676,55 @@ Ctrl+a c           switch between monitor and console
 </code></pre>
 <h2><a class="header" href="#vm-config-snippet" id="vm-config-snippet">VM config snippet</a></h2>
 <p>Following command-line gives a good starting point to assemble a VM:</p>
-<pre><code class="language-bash">qemu-system-x86_64                              \
-        -cpu host -enable-kvm -smp 4            \
-        -m 8G                                   \
-        -vga virtio -display sdl,gl=on          \
-        -boot menu=on                           \
-        -cdrom &lt;iso&gt;                            \
-        -hda &lt;disk&gt;                             \
-        -device qemu-xhci,id=xhci               \
-        -device usb-host,bus=xhci.0,vendorid=0x05e1,productid=0x0408,id=capture-card
+<pre><code>qemu-system-x86_64                 \
+    -cpu host -enable-kvm -smp 4   \
+    -m 8G                          \
+    -vga virtio -display sdl,gl=on \
+    -boot menu=on                  \
+    -cdrom &lt;iso&gt;                   \
+    -hda &lt;disk&gt;                    \
+    -device qemu-xhci,id=xhci      \
+    -device usb-host,bus=xhci.0,vendorid=0x05e1,productid=0x0408,id=capture-card
 </code></pre>
 <h3><a class="header" href="#cpu--ram" id="cpu--ram">CPU &amp; RAM</a></h3>
-<ul>
-<li><code>-cpu host</code> emulate host CPU in guest VM</li>
-<li><code>-enable-kvm</code> use KVM instead software models (requires KVM on host machine)</li>
-<li><code>-smp &lt;N&gt;</code> number of guest CPUs</li>
-</ul>
-<blockquote>
-<p>List available CPUs <code>qemu-system-x86_64 -cpu help</code>.</p>
-</blockquote>
-<ul>
-<li><code>-m 8G</code> size of guest RAM</li>
-</ul>
+<pre><code class="language-bash"># Emulate host CPU in guest VM, enabling all supported host featured (requires KVM).
+# List available CPUs `qemu-system-x86_64 -cpu help`.
+-cpu host
+
+# Enable KVM instead software emulation.
+-enable-kvm
+
+# Configure number of guest CPUs.
+-smp &lt;N&gt;
+
+# Configure size of guest RAM.
+-m 8G
+</code></pre>
 <h3><a class="header" href="#graphic--display" id="graphic--display">Graphic &amp; Display</a></h3>
-<ul>
-<li><code>-vga virtio</code> use virtio as 3D video graphic accelerator (requires virgl in guest)</li>
-<li><code>-display sdl,gl=on</code> use sdl window and enable openGL context</li>
-</ul>
+<pre><code class="language-bash"># Use sdl window as display and enable openGL context.
+-display sdl,gl=on
+
+# Use vnc server as display (eg on display `:42` here).
+-display vnc=localhost:42
+
+# Confifure virtio as 3D video graphic accelerator (requires virgl in guest).
+-vga virtio
+</code></pre>
 <h3><a class="header" href="#boot-menu" id="boot-menu">Boot Menu</a></h3>
-<ul>
-<li><code>-boot menu=on</code> enables boot menu to select boot device (enter with <code>ESC</code>)</li>
-</ul>
+<pre><code class="language-bash"># Enables boot menu to select boot device (enter with `ESC`).
+-boot menu=on
+</code></pre>
 <h3><a class="header" href="#block-devices" id="block-devices">Block devices</a></h3>
-<ul>
-<li><code>-cdrom &lt;iso&gt;</code> attach cdrom drive with iso to a VM</li>
-<li><code>-hda &lt;disk&gt;</code> attach disk drive to a VM</li>
-<li><code>-drive file=&lt;file&gt;,format=qcow2</code> generic way to configure &amp; attach a drive to a VM</li>
-</ul>
-<h4><a class="header" href="#create-a-disk-with-a-hrefhttpsqemureadthedocsioenlatesttoolsqemu-imghtmlqemu-imga" id="create-a-disk-with-a-hrefhttpsqemureadthedocsioenlatesttoolsqemu-imghtmlqemu-imga">Create a disk with <a href="https://qemu.readthedocs.io/en/latest/tools/qemu-img.html"><code>qemu-img</code></a></a></h4>
+<pre><code class="language-bash"># Attach cdrom drive with iso to a VM.
+-cdrom &lt;iso&gt;
+
+# Attach disk drive to a VM.
+-hda &lt;disk&gt;
+
+# Generic way to configure &amp; attach a drive to a VM.
+-drive file=&lt;file&gt;,format=qcow2
+</code></pre>
+<h4><a class="header" href="#create-a-disk-with-a-hrefhttpsqemu-projectgitlabioqemutoolsqemu-imghtmlqemu-imga" id="create-a-disk-with-a-hrefhttpsqemu-projectgitlabioqemutoolsqemu-imghtmlqemu-imga">Create a disk with <a href="https://qemu-project.gitlab.io/qemu/tools/qemu-img.html"><code>qemu-img</code></a></a></h4>
 <p>To create a <code>qcow2</code> disk (qemu copy-on-write) of size <code>10G</code>:</p>
 <pre><code class="language-bash">qemu-img create -f qcow2 disk.qcow2 10G
 </code></pre>
@@ -1733,24 +1749,78 @@ lsblk -f /dev/sda
 </code></pre>
 <h3><a class="header" href="#usb" id="usb">USB</a></h3>
 <h4><a class="header" href="#host-controller" id="host-controller">Host Controller</a></h4>
-<ul>
-<li><code>-device qemu-xhci,id=xhci</code> add XHCI USB controller to the VM (supports USB 3.0, 2.0, 1.1). <code>id=xhci</code> creates a usb bus named <code>xhci</code>.</li>
-</ul>
+<pre><code class="language-bash"># Add XHCI USB controller to the VM (supports USB 3.0, 2.0, 1.1).
+# `id=xhci` creates a usb bus named `xhci`.
+-device qemu-xhci,id=xhci
+</code></pre>
 <h4><a class="header" href="#usb-device" id="usb-device">USB Device</a></h4>
-<ul>
-<li><code>-device usb-host,bus=xhci.0,vendorid=0x05e1,productid=0x0408</code> pass-through USB device from host identified by vendorid &amp; productid and attach to usb bus <code>xhci.0</code> (defined with controller <code>id</code>)</li>
-</ul>
+<pre><code class="language-bash"># Pass-through USB device from host identified by vendorid &amp; productid and
+# attach to usb bus `xhci.0` (defined with controller `id`).
+-device usb-host,bus=xhci.0,vendorid=0x05e1,productid=0x0408
+</code></pre>
 <h2><a class="header" href="#debugging" id="debugging">Debugging</a></h2>
-<ul>
-<li><code>-gdb tcp::&lt;port&gt;</code> open gdbstub on tcp <code>&lt;port&gt;</code> (<code>-s</code> shorthand for <code>-gdb tcp::1234</code>).</li>
-<li><code>-S</code> freeze CPU at startup.</li>
-</ul>
+<pre><code class="language-bash"># Open gdbstub on tcp `&lt;port&gt;` (`-s` shorthand for `-gdb tcp::1234`).
+-gdb tcp::&lt;port&gt;
+
+# Freeze guest CPU at startup and wait for debugger connection.
+-S
+</code></pre>
+<h2><a class="header" href="#io-redirection-2" id="io-redirection-2">IO redirection</a></h2>
+<pre><code class="language-bash"># Create raw tcp server for `serial IO` and wait until a client connects
+# before executing the guest.
+-serial tcp:localhost:12345,server,wait
+
+# Create telnet server for `serial IO` and wait until a client connects
+# before executing the guest.
+-serial telnet:localhost:12345,server,wait
+
+# Configure redirection for the QEMU `mointor`, arguments similar to `-serial`
+# above.
+-monitor ...
+</code></pre>
+<blockquote>
+<p>In <code>server</code> mode use <code>nowait</code> to execute guest without waiting for a client
+connection.</p>
+</blockquote>
+<h2><a class="header" href="#network" id="network">Network</a></h2>
+<pre><code class="language-bash"># Redirect host tcp port `1234` to guest port `4321`.
+-nic user,hostfwd=tcp:localhost:1234-:4321
+</code></pre>
+<h2><a class="header" href="#shared-drives" id="shared-drives">Shared drives</a></h2>
+<pre><code class="language-bash"># Attach a `virtio-9p-pci` device to the VM.
+# The guest requires 9p support and can mount the shared drive as:
+#   mount -t 9p -o trans=virtio someName /mnt
+-virtfs local,id=someName,path=&lt;someHostPath&gt;,mount_tag=someName,security_model=none
+</code></pre>
+<h2><a class="header" href="#tracing" id="tracing">Tracing</a></h2>
+<pre><code class="language-bash"># List name of all trace points.
+-trace help
+
+# Enable trace points matching pattern and optionally write trace to file.
+-trace &lt;pattern&gt;[,file=&lt;file&gt;]
+
+# Enable trace points for all events listed in the &lt;events&gt; file.
+# File must contain one event/pattern per line.
+-trace events=&lt;events&gt;
+</code></pre>
+<h2><a class="header" href="#appendix-direct-kernel-boot" id="appendix-direct-kernel-boot">Appendix: Direct <code>Kernel</code> boot</a></h2>
+<p>Example command line to directly boot a <code>Kernel</code> with an <code>initrd</code> ramdisk.</p>
+<pre><code class="language-bash">qemu-system-x86_64                                                     \
+    -cpu host                                                          \
+    -enable-kvm                                                        \
+    -kernel &lt;dir&gt;/arch/x86/boot/bzImage                                \
+    -append &quot;earlyprintk=ttyS0 console=ttyS0 nokaslr init=/init debug&quot; \
+    -initrd &lt;dir&gt;/initramfs.cpio.gz                                    \
+    ...
+</code></pre>
+<p>Instructions to build a minimal <a href="https://blog.memzero.de/kernel-debugging-qemu"><code>Kernel</code> and <code>initrd</code></a>.</p>
 <h2><a class="header" href="#references" id="references">References</a></h2>
 <ul>
 <li><a href="https://github.com/qemu/qemu/blob/master/docs/usb2.txt">QEMU USB</a></li>
-<li><a href="https://qemu.readthedocs.io/en/latest/tools/qemu-img.html">QEMU IMG</a></li>
-<li><a href="https://qemu.readthedocs.io/en/latest/tools/index.html">QEMU Tools</a></li>
-<li><a href="https://www.qemu.org/docs/master/system/index.html">QEMU System</a></li>
+<li><a href="https://qemu-project.gitlab.io/qemu/tools/qemu-img.html">QEMU IMG</a></li>
+<li><a href="https://qemu-project.gitlab.io/qemu/tools/index.html">QEMU Tools</a></li>
+<li><a href="https://qemu-project.gitlab.io/qemu/system/index.html">QEMU System</a></li>
+<li><a href="https://qemu-project.gitlab.io/qemu/system/invocation.html">QEMU Invocation (command line args)</a></li>
 </ul>
 <h1><a class="header" href="#resource-analysis--monitor" id="resource-analysis--monitor">Resource analysis &amp; monitor</a></h1>
 <ul>
@@ -1897,6 +1967,7 @@ major_pagefault: Happens when the page needed is NOT in memory, the kernel
   -e &lt;expr&gt; ... expression for trace filtering
   -o &lt;file&gt; ... log output into &lt;file&gt;
   -c .......... dump syscall statitics at the end
+  -k .......... dump stack trace for each syscall
 </code></pre>
 <pre><code class="language-markdown">&lt;expr&gt;:
   trace=syscall[,syscall] .... trace only syscall listed