Pileus Git - ~andy/sfvlug/blob - kernel/kernel.tex

   1 \documentclass{beamer}
   2
   3 %%%%%%%%%%%%%%%%%%%
   4 % Commands/macros %
   5 %%%%%%%%%%%%%%%%%%%
   6 \newcommand{\link}[1]{
   7   \begin{flushright}
   8     \scriptsize{#1}
   9   \end{flushright}
  10 }
  11
  12 \newcommand{\hdrs}[1]{\large{\textit{\insertsection}}\\\Large{\textbf{#1}}}
  13 \newcommand{\hdrss}[1]{\large{\textit{\insertsubsection}}\\\large{\textbf{#1}}}
  14
  15 %%%%%%%%%%%%%%%%
  16 % Header/theme %
  17 %%%%%%%%%%%%%%%%
  18 %\usetheme[
  19 %  pageofpages=of,
  20 %  alternativetitlepage=true,
  21 %]{Torino}
  22 %\setbeamertemplate{footline}{}
  23 \setbeamersize{text margin left=10mm}
  24 \setbeamersize{text margin right=5mm}
  25
  26 % Import packages
  27 \usepackage[english]{babel}
  28 \usepackage[latin1]{inputenc}
  29 \usepackage{times}
  30 \usepackage[T1]{fontenc}
  31 \usepackage{graphics}
  32 \usepackage{hyperref}
  33 \usepackage{ulem}
  34 \usepackage{color}
  35 \usepackage{listings}
  36 \usepackage{xcolor}
  37
  38 % Diff syntax
  39 \definecolor{diffcommit}{rgb}{.50, .50, .00}
  40 \definecolor{diffauthor}{rgb}{.50, .50, .00}
  41 \definecolor{diffdate}  {rgb}{.50, .50, .00}
  42 \definecolor{diffdiff}  {rgb}{.30, .30, .90}
  43 \definecolor{diffindex} {rgb}{.50, .00, .50}
  44 \definecolor{diffstart} {rgb}{.00, .50, .50}
  45 \definecolor{diffadd}   {rgb}{.00, .60, .00}
  46 \definecolor{diffdel}   {rgb}{.80, .00, .00}
  47
  48 \lstdefinelanguage{diff}{
  49   basicstyle=\ttfamily\small,
  50   morecomment=[f][\color{diffcommit}]{commit},
  51   morecomment=[f][\color{diffauthor}]{Author},
  52   morecomment=[f][\color{diffdate}]{Date},
  53   morecomment=[f][\color{diffdiff}]{diff},
  54   morecomment=[f][\color{diffindex}]{index},
  55   morecomment=[f][\color{diffstart}]{@@},
  56   morecomment=[f][\color{diffadd}]{+},
  57   morecomment=[f][\color{diffdel}]{-},
  58   morecomment=[f][\color{diffindex}]{+++},
  59   morecomment=[f][\color{diffindex}]{---},
  60 }
  61
  62 \lstset{language=diff,
  63         basicstyle=\ttfamily,
  64         keywordstyle=\color{blue}\ttfamily,
  65         stringstyle=\color{red}\ttfamily,
  66         commentstyle=\color{green}\ttfamily,
  67         morecomment=[l][\color{magenta}]{\#} }
  68
  69 %%%%%%%%%%%%%%%%%%%%
  70 % Title page setup %
  71 %%%%%%%%%%%%%%%%%%%%
  72 \subject{%
  73   kernel,
  74   programming
  75 }
  76
  77 \keywords{%
  78   linux,
  79   kernel
  80 }
  81
  82 \title[Kernel Programming]{%
  83   Introduction to Linux Kernel Programming
  84 }
  85
  86 \author[Spencer]{%
  87   Andy Spencer
  88 }
  89
  90 \date[2020-01-04]{%
  91   Jan. 4, 2020 \\
  92   \small{San Fernando Valley Linux Users Group}
  93 }
  94
  95 %%%%%%%%%%%%%%%%%
  96 % Content pages %
  97 %%%%%%%%%%%%%%%%%
  98 % Structure:
  99 %   - Examples
 100 %     - The typo fix
 101 %     - The hardware id
 102 %     - The driver debug
 103 %     - The new driver
 104 %     - The new protocol
 105 %     - The new board
 106 %   - Development
 107 %     - Kernel compiling
 108 %     - Booting the kernel
 109 %     - Kernel source tree
 110 %     - Sending patches
 111 %   - Kernel modules
 112 %     - Hello, World
 113 %     - User Interfaces
 114 %       - printk / dmesg
 115 %       - /dev, proc, sysfs
 116 %       - syscalls, ioctls
 117 %     - Devices and Drivers
 118 \begin{document}
 119
 120 %%%%%%%%%%%%%%%%
 121 % Introduction %
 122 %%%%%%%%%%%%%%%%
 123 \begin{frame}[plain]
 124   \titlepage
 125 \end{frame}
 126
 127 % Examples
 128 % - The typo fix
 129 % - The hardware id
 130 % - The driver debug
 131 % - The new driver
 132 % - The new protocol
 133 % - The new board
 134
 135 \section{Examples Patches}
 136
 137 \begin{frame}[fragile]{\hdrs{The Typo Fix}}
 138   \begin{lstlisting}[language=diff,basicstyle=\tiny]
 139 commit 9eac0ae1683575375de8c63166b3596b11d3b56a
 140 Author: Krzysztof Kozlowski <krzk@kernel.org>
 141 Date:   2019-01-08 13:11:40 +0100
 142
 143     dt-bindings: soc: qcom: Fix trivial language typos
 144
 145     Fix few trivial language typos in bindings.
 146
 147     Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
 148     Signed-off-by: Rob Herring <robh@kernel.org>
 149
 150 diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom,glink.txt b/Docume...
 151 index 0b8cc533ca83..cf759e5f9b10 100644
 152 --- a/Documentation/devicetree/bindings/soc/qcom/qcom,glink.txt
 153 +++ b/Documentation/devicetree/bindings/soc/qcom/qcom,glink.txt
 154 @@ -55,7 +55,7 @@ of these nodes are defined by the individual bindings for the...
 155  = EXAMPLE
 156  The following example represents the GLINK RPM node on a MSM8996 device, with
 157  the function for the "rpm_request" channel defined, which is used for
 158 -regualtors and root clocks.
 159 +regulators and root clocks.
 160
 161         apcs_glb: mailbox@9820000 {
 162                 compatible = "qcom,msm8996-apcs-hmss-global";
 163   \end{lstlisting}
 164 \end{frame}
 165
 166 \begin{frame}[fragile]{\hdrs{The Hardware ID}}
 167   \begin{lstlisting}[language=diff,basicstyle=\tiny]
 168 commit 7ab21a8692094872298df172f54d55cba72fd308
 169 Author: Andy Spencer <spenceal@rose-hulman.edu>
 170 Date:   2009-01-02 16:19:13 +0000
 171
 172     i8k: Enable i8k on Dell Precision Systems
 173
 174     Patch to enable i8k on Dell Precisions.
 175
 176     Signed-off-by: Andy Spencer <spenceal@rose-hulman.edu>
 177     Signed-off-by: Alan Cox <alan@redhat.com>
 178     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 179
 180 diff --git a/drivers/char/i8k.c b/drivers/char/i8k.c
 181 index b60d425ce8d1..099fc89a5bdd 100644
 182 --- a/drivers/char/i8k.c
 183 +++ b/drivers/char/i8k.c
 184 @@ -485,6 +485,13 @@ static struct dmi_system_id __initdata i8k_dmi_table[] = {
 185                         DMI_MATCH(DMI_PRODUCT_NAME, "MP061"),
 186                 },
 187         },
 188 +       {
 189 +               .ident = "Dell Precision",
 190 +               .matches = {
 191 +                       DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 192 +                       DMI_MATCH(DMI_PRODUCT_NAME, "Precision"),
 193 +               },
 194 +       },
 195         { }
 196  };
 197   \end{lstlisting}
 198 \end{frame}
 199
 200 \begin{frame}[fragile]{\hdrs{The Driver Debug}}
 201   \begin{lstlisting}[language=diff,basicstyle=\tiny]
 202 commit ab1796ebdad3017965754d86db64d3cba5c416b9
 203 Author: Andy Spencer <andy753421@ucla.edu>
 204 Date:   2014-05-02 06:48:13 +0000
 205
 206     RTL8192CU: Increase max APFM_ONMAC polling count
 207
 208     With certain hardware combinations the poll interval is exceeded before
 209     initialization completes.
 210
 211     Tested on a MacBookPro10,1 using a Sabrent USB-A11N USB adapter.
 212
 213     Signed-off-by: Andy Spencer <andy753421@ucla.edu>
 214     Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
 215     Signed-off-by: John W. Linville <linville@tuxdriver.com>
 216
 217 diff --git a/drivers/net/wireless/rtlwifi/rtl8192cu/hw.c b/drivers/net/wireless/rtlw...
 218 index 68b5c7e92cfb..31b79e78c63c 100644
 219 --- a/drivers/net/wireless/rtlwifi/rtl8192cu/hw.c
 220 +++ b/drivers/net/wireless/rtlwifi/rtl8192cu/hw.c
 221 @@ -511,7 +511,7 @@ static int _rtl92cu_init_power_on(struct ieee80211_hw *hw)
 222                         pr_info("MAC auto ON okay!\n");
 223                         break;
 224                 }
 225 -               if (pollingCount++ > 100) {
 226 +               if (pollingCount++ > 1000) {
 227                         RT_TRACE(rtlpriv, COMP_INIT, DBG_EMERG,
 228                                  "Failed to polling REG_APS_FSMCO[APFM_ONMAC] done!\n");
 229                         return -ENODEV;
 230   \end{lstlisting}
 231 \end{frame}
 232
 233 \begin{frame}[fragile]{\hdrs{The New Protocol}}
 234   \begin{itemize}
 235     \item New network protocols, filesystems, security modules, etc.
 236     \item Software only improvmenets to the kernel.
 237     \item No hardware required, can be tested in a VM.
 238     \item Typocally done in net/, fs/, security/, etc.
 239   \end{itemize}
 240 \end{frame}
 241
 242 \begin{frame}[fragile]{\hdrs{The New Driver}}
 243   \begin{itemize}
 244     \item Add support for a new hardware device.
 245     \item Cononical example: I2C/SPI thermal sensors. (lm70.c)
 246     \item Find the data sheet
 247     \item Typocally use an existing driver as an example.
 248     \item Requires hardware to test on.
 249     \item Typocally done in drivers/.
 250   \end{itemize}
 251 \end{frame}
 252
 253 \begin{frame}[fragile]{\hdrs{The New Board}}
 254   \begin{itemize}
 255     \item Simmilar new drivers but focuse on boot.
 256     \item Typocally for embedded Linux.
 257     \item May require bootloader changes.
 258     \item Typocally done in arch/.
 259   \end{itemize}
 260 \end{frame}
 261
 262 % Development
 263 % - Kernel compiling
 264 % - Booting the kernel
 265 % - Kernel source tree
 266 % - Sending patches
 267
 268 \section{Development}
 269
 270 \begin{frame}{\hdrs{Kernel compiling}}
 271   Could be an entire talk on it's own...
 272
 273   \begin{itemize}
 274     \item \$ make menuconfig
 275     \item \$ make -j32
 276     \item \$ make install
 277       \begin{itemize}
 278         \item invokes \$HOME/bin/installkernel
 279       \end{itemize}
 280     \item \$ make modules\_install
 281   \end{itemize}
 282
 283   Output files:
 284   \begin{itemize}
 285     \item vmlinux: Main build output, ELF file with debug symbols.
 286     \item bzImage: Bootable kernel image (wraps vmlinux).
 287     \item uImage, etc: Like bzImage for other architctures.
 288   \end{itemize}
 289
 290 \end{frame}
 291
 292 \begin{frame}{\hdrs{Booting the kernel}}
 293   How to test?
 294
 295   \begin{enumerate}
 296     \item Compile, reboot, compile, reboot..
 297       \begin{itemize}
 298         \item Least efficient, but often needed for debugging.
 299       \end{itemize}
 300     \item Run the kenrel it in a VM.
 301       \begin{itemize}
 302         \item Great for experimenting.
 303         \item Won't work for for driver.
 304       \end{itemize}
 305     \item Dynamic kernel module loading.
 306       \begin{itemize}
 307         \item Good for most driver work.
 308         \item Easy to crash your PC.
 309       \end{itemize}
 310     \item Boot it on a dedicated machine.
 311       \begin{itemize}
 312         \item Generally used for embedded Linux.
 313         \item Prevents crashing your workstation.
 314       \end{itemize}
 315   \end{enumerate}
 316 \end{frame}
 317
 318 \begin{frame}{\hdrs{Kernel source tree}}
 319   \begin{itemize}
 320     \item arch/: architecture specific code
 321     \item drivers/: well... drivers
 322     \item fs/: file systems
 323     \item kernel/: core kernel code (process management, etc)
 324     \item lib/: utility code, C library type stuff
 325     \item mm/: memroy management
 326     \item include/: shared include files
 327   \end{itemize}
 328 \end{frame}
 329
 330 \begin{frame}{\hdrs{Sending patches}}
 331   \url{https://www.kernel.org/doc/html/latest/process/submitting-patches.html}
 332   \begin{itemize}
 333     \item Linux uses mailing lists patches and code review.
 334     \item Maintainers tend to use pull requests and merges, but general
 335       contributors usually do not.
 336     \item Different subsystem (netdev) have slightly different rules.
 337     \item Patchwork is useful for tracking and reviewing patches:
 338       \url{https://patchwork.kernel.org}
 339   \end{itemize}
 340 \end{frame}
 341
 342 % Kernel modules
 343 % - Hello, World
 344 % - User Interfaces
 345 %   - printk / dmesg
 346 %   - /dev, proc, sysfs
 347 %   - syscalls, ioctls
 348 % - Devices and Drivers
 349
 350 \section{Kernel Modules}
 351
 352 \begin{frame}[fragile]{\hdrs{Hello, World}}
 353   \begin{lstlisting}[language=C,basicstyle=\scriptsize]
 354 #include <linux/module.h>
 355 #include <linux/kernel.h>
 356 #include <linux/init.h>
 357
 358 static int __init hello_init(void)
 359 {
 360         pr_info("Hello SFVLUG.\n");
 361         return 0;
 362 }
 363
 364 static void __exit hello_exit(void)
 365 {
 366         pr_info("Goodbye SFVLUG.\n");
 367 }
 368
 369 module_init(hello_init);
 370 module_exit(hello_exit);
 371
 372 MODULE_LICENSE("GPL");
 373 MODULE_AUTHOR("Andy Spencer <andy753421@gmail.com>");
 374 MODULE_DESCRIPTION("SFVLUG!");
 375   \end{lstlisting}
 376 \end{frame}
 377
 378 %\begin{frame}[fragile]{\hdrs{Makefile / Kconfig}}
 379 %  \begin{lstlisting}[Building it]
 380 %  \end{lstlisting}
 381 %\end{frame}
 382 %
 383 %\begin{frame}{\hdrs{User Interfaces}}
 384 %- printk / dmesg
 385 %- /dev, proc, sysfs
 386 %- syscalls, ioctls
 387 %\end{frame}
 388 %
 389 %\begin{frame}{\hdrs{Devices and Drivers}}
 390 %\end{frame}
 391
 392 \end{document}