diff --git a/doc/lab-01_02.typ b/doc/lab-01_02.typ index 88c4092..6e809dc 100644 --- a/doc/lab-01_02.typ +++ b/doc/lab-01_02.typ @@ -1,5 +1,5 @@ // #import "@preview/hei-synd-report:0.1.1": * -#import "@preview/hei-synd-thesis:0.3.1": * +#import "@preview/hei-synd-thesis:0.4.0": * #import "/doc/metadata.typ": * #import "/doc/resources/glossary.typ": * #show:make-glossary @@ -56,7 +56,10 @@ In this laboratory, we see how to setup our environnement and how to have severa We also see how to debug our system with a remote debugger. That allow us to use debug in our code editor (vscode) a programm that run on the target. -// PLACEHOLEDER SCHEMA +#figure( + image("/doc/resources/img/dev-environment.drawio.svg"), + caption: "Development environment schema" +) == Questions @@ -99,6 +102,19 @@ If we develop only user space program, we don't need to load kernel by tftp. But #pagebreak() = Linux Kernel Programming +== Cheatsheet commands +- `modinfo `: display information about a kernel module +- `insmod `: install a kernel module (without checking for dependencies) +- `rmmod `: uninstall a kernel module +- `lsmod`: list the currently loaded kernel modules +- `dmesg`: display the kernel log +- `cat /proc/modules`: display the currently loaded kernel modules with more details +- `modprobe `: install a kernel module and its dependencies +- `modprobe -r `: uninstall a kernel module and its dependencies +- `make`: build the kernel module +- `make install`: install the kernel module in the root filesystem + + == Exercises //------------------- @@ -114,7 +130,7 @@ If we develop only user space program, we don't need to load kernel by tftp. But Create the skeleton of a kernel module and generate it outside the kernel sources using a Makefile. The module should display a message when it is registered and when it is uninstalled. ] -We already have a skeleton in `src/02-modules/exercice01`. We see on the Makefile that the module is generated outside the kernel sources with the `KDIR` variable imported from `src/kernel_settings`. This variable point to the kernel sources. +We already have a skeleton in `src/02-modules/exercice01` (now `solutions/02_modules/exercice01` that we move to `src/01-skeleton`). We see on the Makefile that the module is generated outside the kernel sources with the `KDIR` variable imported from `src/kernel_settings`. This variable point to the kernel sources. The Makefile also use the `PWD` variable to the current directory. The `make` command will use these variables to generate the module in the current directory. @@ -129,11 +145,12 @@ $(MAKE) -C $(KDIR) M=$(PWD) ARCH=$(CPU) CROSS_COMPILE=$(TOOLS) modules ```bash |> modinfo mymodule.ko -filename: /workspace/src/02_modules/exercice01/mymodule.ko +filename: /workspace/src/01-skeleton/mymodule.ko license: GPL description: Module skeleton -author: Daniel Gachet -depends: +author: Klagarge +author: Fastium +depends: name: mymodule vermagic: 5.15.148 SMP preempt mod_unload aarch64 parm: text:charp @@ -174,6 +191,7 @@ mymodule 16384 0 mymodule 16384 0 - Live 0xffff8000011bf000 (O) ··· ``` +The `/proc/modules` file give us more details about the state of the module. We see it is now live (charged in memory and running) //-------------- #subtask[ @@ -199,6 +217,7 @@ mymodule 16384 0 - Live 0xffff8000011bf000 (O) [ 3359.811183] Linux module 01 skeleton loaded ``` +#pagebreak() //------------------- // Exercise 2: Adapt the kernel module to receive parameters //------------------- @@ -209,13 +228,26 @@ mymodule 16384 0 - Live 0xffff8000011bf000 (O) ], ) +```bash +|> modprobe mymodule +[ 3583.616662] Linux module skeleton ex02 loaded +|> dmesg | tail -5 +[ 3559.279143] number: 1 +[ 3581.198562] Linux module skeleton unloaded +[ 3583.616662] Linux module skeleton ex02 loaded +[ 3583.621085] text: The answer to the Ultimate Question of Life, The Universe, and Everything +[ 3583.621085] number: 42 +|> modprobe -r mymodule +[ 3588.404778] Linux module skeleton unloaded + +``` + //------------------- // Exercise 3: What does it mean the 4 values in ```/proc/sys/kernel/printk``` ? //------------------- #task( [What does it mean the 4 values in ```/proc/sys/kernel/printk``` ?], - [ - ] + [] ) We can show what there is in: @@ -226,15 +258,29 @@ We can show what there is in: ``` The number specified the level of output in a console. -This file specifies the log level for: -- current: 7 -- default: 4 -- minimum: 1 -- boot-time-default: 7 +This file specifies the log level for: \ +current (7), default (4), minimum (1) and boot-time default (7). This number matches with this table (#link("https://www.kernel.org/doc/html/latest/core-api/printk-basics.html", [printk documentation])): -#image("resources/img/printk-log-levels.png") +#table( + columns: (2fr, 1fr, 3fr), + + [*Name*], [*String*], [*Alias function*], + + [KERN_EMERG], ["0"], [pr_emerg()], + [KERN_ALERT], ["1"], [pr_alert()], + [KERN_CRIT], ["2"], [pr_crit()], + [KERN_ERR], ["3"], [pr_err()], + [KERN_WARNING], ["4"], [pr_warning()], + [KERN_NOTICE], ["5"], [pr_notice()], + [KERN_INFO], ["6"], [pr_info()], + [KERN_DEBUG], ["7"], [pr_debug() and pr_devel() if DEBUG is defined], + [KERN_DEFAULT], [""], [], + [KERN_CONT], ["c"], [pr_cont()], +) + +#pagebreak() //------------------- // Exercise 4: Create module with dynamic allocation and a chained list //------------------- diff --git a/doc/resources/img/dev-environment.drawio.svg b/doc/resources/img/dev-environment.drawio.svg new file mode 100644 index 0000000..965744f --- /dev/null +++ b/doc/resources/img/dev-environment.drawio.svg @@ -0,0 +1 @@ +
SSH / Serial
SSH / Serial
Docker compose / host
Docker compose / host
Nanopi
Nanopi
SD card
SD card
Ram
Ram
Kernel
Kernel
DeviceTree
DeviceTree
U-Boot
U-Boot
Kernel
Kernel
deviceTree
deviceTree
rootfs
rootfs
toolchain
toolchain
samba
samba
tftp
tftp
/buildroot
/buildroot
 /workspace
 /workspace
 /rootfs
 /rootfs
kernel
kernel
deviceTree
deviceTree
load from SD card
load from S...
Extract
Extract
/buildroot
/buildroot
 /workspace
 /workspace
 /rootfs
 /rootfs
Download at boot time
Download at...
Mount at boot time
Mount at b...
Mount with fstab
Mount with fstab
Mount
Mount
rootfs
rootfs
/workspace
/workspace
kernel
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