get rid of lkmc package, move userland and kernel-modules to top

Rationale: we already had a non buildroot build system,
maintaining both will be hard, and having short paths is more awesome.

README.adoc

@@ -123,8 +123,8 @@ which are `printk` messages from `init` and `cleanup` methods of those modules.
 
 Sources:
 
-* link:packages/lkmc/kernel_modules/hello.c[]
+* link:kernel_modules/hello.c[]
-* link:packages/lkmc/kernel_modules/hello2.c[]
+* link:kernel_modules/hello2.c[]
 
 Quit QEMU with:
 
@@ -134,7 +134,7 @@ Ctrl-A X
 
 See also: <<quit-qemu-from-text-mode>>.
 
-All available modules can be found in the link:packages/lkmc/kernel_modules[] directory.
+All available modules can be found in the link:kernel_modules[] directory.
 
 It is super easy to build for different CPU architectures, just use the `--arch` option:
 
@@ -245,7 +245,7 @@ So you are now officially a Linux kernel hacker, way to go!
 
 ===== Your first kernel module hack
 
-Edit link:packages/lkmc/kernel_modules/hello.c[] to contain:
+Edit link:kernel_modules/hello.c[] to contain:
 
 ....
 pr_info("hello init hacked\n");
@@ -1124,7 +1124,7 @@ Wait for the boot to end and run:
 insmod /timer.ko
 ....
 
-Source: link:packages/lkmc/kernel_modules/timer.c[].
+Source: link:kernel_modules/timer.c[].
 
 This prints a message to dmesg every second.
 
@@ -1695,7 +1695,7 @@ We can set and get which cores the Linux kernel allows a program to run on with
 ./run --cpus 2 --eval-busybox '/sched_getaffinity.out'
 ....
 
-Source: link:packages/lkmc/userland/sched_getaffinity.c[]
+Source: link:userland/sched_getaffinity.c[]
 
 Sample output:
 
@@ -2199,9 +2199,9 @@ traps: ring0.out[55] general protection ip:40054c sp:7fffffffec20 error:0 in rin
 
 Sources:
 
-* link:packages/lkmc/kernel_modules/ring0.c[]
+* link:kernel_modules/ring0.c[]
-* link:packages/lkmc/kernel_modules/ring0.h[]
+* link:kernel_modules/ring0.h[]
-* link:packages/lkmc/userland/ring0.c[]
+* link:userland/ring0.c[]
 
 In both cases, we attempt to run the exact same code which is shared on the `ring0.h` header file.
 
@@ -2351,7 +2351,7 @@ but why not just use our minimal `/poweroff.out` and be done with it?
 ./run --eval '/poweroff.out'
 ....
 
-Source: link:packages/lkmc/userland/poweroff.c[]
+Source: link:userland/poweroff.c[]
 
 This also illustrates how to shutdown the computer from C: https://stackoverflow.com/questions/28812514/how-to-shutdown-linux-using-c-or-qt-without-call-to-system
 
@@ -2363,7 +2363,7 @@ I dare you to guess what this does:
 ./run --eval '/sleep_forever.out'
 ....
 
-Source: link:packages/lkmc/userland/sleep_forever.c[]
+Source: link:userland/sleep_forever.c[]
 
 This executable is a convenient simple init that does not panic and sleeps instead.
 
@@ -2456,7 +2456,7 @@ TERM=linux
 asdf=qwer
 ....
 
-Source: link:packages/lkmc/userland/init_env_poweroff.c[].
+Source: link:userland/init_env_poweroff.c[].
 
 ==== init environment args
 
@@ -2867,7 +2867,7 @@ If you are feeling fancy, you can also insert modules with:
 modprobe hello
 ....
 
-which insmods link:packages/lkmc/kernel_modules/hello.c[].
+which insmods link:kernel_modules/hello.c[].
 
 `modprobe` searches for modules under:
 
@@ -2897,8 +2897,8 @@ which teaches you how it is done from C code.
 
 Source:
 
-* link:packages/lkmc/userland/myinsmod.c[]
+* link:userland/myinsmod.c[]
-* link:packages/lkmc/userland/myrmmod.c[]
+* link:userland/myrmmod.c[]
 
 The Linux kernel offers two system calls for module insertion:
 
@@ -4124,7 +4124,7 @@ echo 'module myprintk +p' > /sys/kernel/debug/dynamic_debug/control
 insmod /myprintk.ko
 ....
 
-Source: link:packages/lkmc/kernel_modules/myprintk.c[]
+Source: link:kernel_modules/myprintk.c[]
 
 This outputs the `pr_debug` message:
 
@@ -4215,7 +4215,7 @@ Outcome: the test passes:
 
 Sources:
 
-* link:packages/lkmc/kernel_modules/params.c[]
+* link:kernel_modules/params.c[]
 * link:rootfs_overlay/params.sh[]
 
 As shown in the example, module parameters can also be read and modified at runtime from <<sysfs>>.
@@ -4269,8 +4269,8 @@ Outcome: the test passes:
 
 Sources:
 
-* link:packages/lkmc/kernel_modules/dep.c[]
+* link:kernel_modules/dep.c[]
-* link:packages/lkmc/kernel_modules/dep2.c[]
+* link:kernel_modules/dep2.c[]
 * link:rootfs_overlay/dep.sh[]
 
 The kernel deduces dependencies based on the `EXPORT_SYMBOL` that each module uses.
@@ -4368,7 +4368,7 @@ name = module_info
 version = 1.0
 ....
 
-Source: link:packages/lkmc/kernel_modules/module_info.c[]
+Source: link:kernel_modules/module_info.c[]
 
 Some of those are also present on sysfs:
 
@@ -4454,7 +4454,7 @@ Possible dmesg output:
 VERMAGIC_STRING = 4.17.0 SMP mod_unload modversions
 ....
 
-Source: link:packages/lkmc/kernel_modules/vermagic.c[]
+Source: link:kernel_modules/vermagic.c[]
 
 If we artificially create a mismatch with `MODULE_INFO(vermagic`, the insmod fails with:
 
@@ -4468,7 +4468,7 @@ and `dmesg` says the expected and found vermagic found:
 vermagic_fail: version magic 'asdfqwer' should be '4.17.0 SMP mod_unload modversions '
 ....
 
-Source: link:packages/lkmc/kernel_modules/vermagic_fail.c[]
+Source: link:kernel_modules/vermagic_fail.c[]
 
 The kernel's vermagic is defined based on compile time configurations at link:https://github.com/torvalds/linux/blob/v4.17/include/linux/vermagic.h#L35[include/linux/vermagic.h]:
 
@@ -4516,7 +4516,7 @@ init_module
 cleanup_module
 ....
 
-Source: link:packages/lkmc/kernel_modules/module_init.c[]
+Source: link:kernel_modules/module_init.c[]
 
 TODO why were `module_init` and `module_exit` created? https://stackoverflow.com/questions/3218320/what-is-the-difference-between-module-init-and-init-module-in-a-linux-kernel-mod
 
@@ -4531,8 +4531,8 @@ insmod /oops.ko
 
 Source:
 
-* link:packages/lkmc/kernel_modules/panic.c[]
+* link:kernel_modules/panic.c[]
-* link:packages/lkmc/kernel_modules/oops.c[]
+* link:kernel_modules/oops.c[]
 
 A panic can also be generated with:
 
@@ -4869,7 +4869,7 @@ The `dump_stack` function produces a stack trace much like panic and oops, but c
 insmod /dump_stack.ko
 ....
 
-Source: link:packages/lkmc/kernel_modules/dump_stack.c[]
+Source: link:kernel_modules/dump_stack.c[]
 
 ==== WARN_ON
 
@@ -4882,7 +4882,7 @@ echo 1 > /proc/sys/kernel/panic_on_warn
 insmod /warn_on.ko
 ....
 
-Source: link:packages/lkmc/kernel_modules/warn_on.c[]
+Source: link:kernel_modules/warn_on.c[]
 
 Can also be activated with the `panic_on_warn` boot parameter.
 
@@ -4914,7 +4914,7 @@ Outcome: the test passes:
 
 Sources:
 
-* link:packages/lkmc/kernel_modules/debugfs.c[]
+* link:kernel_modules/debugfs.c[]
 * link:rootfs_overlay/debugfs.sh[]
 
 Debugfs is made specifically to help test kernel stuff. Just mount, set <<file-operations>>, and we are done.
@@ -4955,7 +4955,7 @@ Procfs can run all system calls, including ones that debugfs can't, e.g. <<mmap>
 
 Sources:
 
-* link:packages/lkmc/kernel_modules/procfs.c[]
+* link:kernel_modules/procfs.c[]
 * link:rootfs_overlay/procfs.sh[]
 
 Bibliography: https://stackoverflow.com/questions/8516021/proc-create-example-for-kernel-module/18924359#18924359
@@ -4977,7 +4977,7 @@ Outcome: the test passes:
 
 Sources:
 
-* link:packages/lkmc/kernel_modules/sysfs.c[]
+* link:kernel_modules/sysfs.c[]
 * link:rootfs_overlay/sysfs.sh[]
 
 Vs procfs:
@@ -5018,7 +5018,7 @@ Sources:
 
 * link:rootfs_overlay/character_device.sh[]
 * link:rootfs_overlay/mknoddev.sh[]
-* link:packages/lkmc/kernel_modules/character_device.c[]
+* link:kernel_modules/character_device.c[]
 
 Unlike <<procfs>> entires, character device files are created with userland `mknod` or `mknodat` syscalls:
 
@@ -5071,7 +5071,7 @@ Outcome: the test passes:
 
 Sources:
 
-* link:packages/lkmc/kernel_modules/character_device_create.c[]
+* link:kernel_modules/character_device_create.c[]
 * link:rootfs_overlay/character_device_create.sh[]
 
 Bibliography: https://stackoverflow.com/questions/5970595/how-to-create-a-device-node-from-the-init-module-code-of-a-linux-kernel-module/45531867#45531867
@@ -5097,7 +5097,7 @@ Outcome: the test passes:
 
 Sources:
 
-* link:packages/lkmc/kernel_modules/fops.c[]
+* link:kernel_modules/fops.c[]
 * link:rootfs_overlay/fops.sh[]
 
 Then give this a try:
@@ -5127,7 +5127,7 @@ Outcome: the test passes:
 
 Sources:
 
-* link:packages/lkmc/kernel_modules/seq_file.c[]
+* link:kernel_modules/seq_file.c[]
 * link:rootfs_overlay/seq_file.sh[]
 
 In this example we create a debugfs file that behaves just like a file that contains:
@@ -5164,7 +5164,7 @@ Outcome: the test passes:
 
 Sources:
 
-* link:packages/lkmc/kernel_modules/seq_file_single_open.c[]
+* link:kernel_modules/seq_file_single_open.c[]
 * link:rootfs_overlay/seq_file_single_open.sh[]
 
 This example produces a debugfs file that behaves like a file that contains:
@@ -5186,8 +5186,8 @@ Outcome: `jiffies` gets printed to stdout every second from userland.
 
 Sources:
 
-* link:packages/lkmc/kernel_modules/poll.c[]
+* link:kernel_modules/poll.c[]
-* link:packages/lkmc/kernel_modules/poll.c[]
+* link:kernel_modules/poll.c[]
 * link:rootfs_overlay/poll.sh[]
 
 Typically, we are waiting for some hardware to make some piece of data available available to the kernel.
@@ -5215,9 +5215,9 @@ Outcome: the test passes:
 
 Sources:
 
-* link:packages/lkmc/kernel_modules/ioctl.c[]
+* link:kernel_modules/ioctl.c[]
-* link:packages/lkmc/kernel_modules/ioctl.h[]
+* link:kernel_modules/ioctl.h[]
-* link:packages/lkmc/userland/ioctl.c[]
+* link:userland/ioctl.c[]
 * link:rootfs_overlay/ioctl.sh[]
 
 `ioctl` is one of the most important methods of communication with real device drivers, which often take several fields as input.
@@ -5264,8 +5264,8 @@ Outcome: the test passes:
 
 Sources:
 
-* link:packages/lkmc/kernel_modules/mmap.c[]
+* link:kernel_modules/mmap.c[]
-* link:packages/lkmc/userland/mmap.c[]
+* link:userland/mmap.c[]
 * link:rootfs_overlay/mmap.sh[]
 
 In this example, we make a tiny 4 byte kernel buffer available to user-space, and we then modify it on userspace, and check that the kernel can see the modification.
@@ -5300,9 +5300,9 @@ Outcome: the test passes:
 
 Sources:
 
-* link:packages/lkmc/kernel_modules/anonymous_inode.c[]
+* link:kernel_modules/anonymous_inode.c[]
-* link:packages/lkmc/kernel_modules/anonymous_inode.h[]
+* link:kernel_modules/anonymous_inode.h[]
-* link:packages/lkmc/userland/anonymous_inode.c[]
+* link:userland/anonymous_inode.c[]
 * link:rootfs_overlay/anonymous_inode.sh[]
 
 This example gets an anonymous inode via <<ioctl>> from a debugfs entry by using `anon_inode_getfd`.
@@ -5328,9 +5328,9 @@ Outcome: the test passes:
 
 Sources:
 
-* link:packages/lkmc/kernel_modules/netlink.c[]
+* link:kernel_modules/netlink.c[]
-* link:packages/lkmc/kernel_modules/netlink.h[]
+* link:kernel_modules/netlink.h[]
-* link:packages/lkmc/userland/netlink.c[]
+* link:userland/netlink.c[]
 * link:rootfs_overlay/netlink.sh[]
 
 Launch multiple user requests in parallel to stress our socket:
@@ -5355,7 +5355,7 @@ Kernel threads are managed exactly like userland threads; they also have a backi
 insmod /kthread.ko
 ....
 
-Source: link:packages/lkmc/kernel_modules/kthread.c[]
+Source: link:kernel_modules/kthread.c[]
 
 Outcome: dmesg counts from `0` to `9` once every second infinitely many times:
 
@@ -5393,7 +5393,7 @@ Let's launch two threads and see if they actually run in parallel:
 insmod /kthreads.ko
 ....
 
-Source: link:packages/lkmc/kernel_modules/kthreads.c[]
+Source: link:kernel_modules/kthreads.c[]
 
 Outcome: two threads count to dmesg from `0` to `9` in parallel.
 
@@ -5427,7 +5427,7 @@ Count to dmesg every one second from `0` up to `n - 1`:
 insmod /sleep.ko n=5
 ....
 
-Source: link:packages/lkmc/kernel_modules/sleep.c[]
+Source: link:kernel_modules/sleep.c[]
 
 The sleep is done with a call to link:https://github.com/torvalds/linux/blob/v4.17/kernel/time/timer.c#L1984[`usleep_range`] directly inside `module_init` for simplicity.
 
@@ -5452,7 +5452,7 @@ Stop counting:
 rmmod workqueue_cheat
 ....
 
-Source: link:packages/lkmc/kernel_modules/workqueue_cheat.c[]
+Source: link:kernel_modules/workqueue_cheat.c[]
 
 The workqueue thread is killed after the worker function returns.
 
@@ -5476,7 +5476,7 @@ rmmod work_from_work
 
 The sleep is done indirectly through: link:https://github.com/torvalds/linux/blob/v4.17/include/linux/workqueue.h#L522[`queue_delayed_work`], which waits the specified time before scheduling the work.
 
-Source: link:packages/lkmc/kernel_modules/work_from_work.c[]
+Source: link:kernel_modules/work_from_work.c[]
 
 ==== schedule
 
@@ -5488,7 +5488,7 @@ Let's block the entire kernel! Yay:
 
 Outcome: the system hangs, the only way out is to kill the VM.
 
-Source: link:packages/lkmc/kernel_modules/schedule.c[]
+Source: link:kernel_modules/schedule.c[]
 
 kthreads only allow interrupting if you call `schedule()`, and the `schedule=0` <<kernel-module-parameters,kernel module parameter>> turns it off.
 
@@ -5544,7 +5544,7 @@ Stop the count:
 rmmod wait_queue
 ....
 
-Source: link:packages/lkmc/kernel_modules/wait_queue.c[]
+Source: link:kernel_modules/wait_queue.c[]
 
 This example launches three threads:
 
@@ -5572,7 +5572,7 @@ Stop counting:
 rmmod timer
 ....
 
-Source: link:packages/lkmc/kernel_modules/timer.c[]
+Source: link:kernel_modules/timer.c[]
 
 Timers are callbacks that run when an interrupt happens, from the interrupt context itself.
 
@@ -5593,7 +5593,7 @@ Brute force monitor every shared interrupt that will accept us:
 ./run --eval-busybox 'insmod /irq.ko' --graphic
 ....
 
-Source: link:packages/lkmc/kernel_modules/irq.c[].
+Source: link:kernel_modules/irq.c[].
 
 Now try the following:
 
@@ -5737,7 +5737,7 @@ Outcome: the test passes:
 
 Sources:
 
-* link:packages/lkmc/kernel_modules/kstrto.c[]
+* link:kernel_modules/kstrto.c[]
 * link:rootfs_overlay/kstrto.sh[]
 
 Bibliography: https://stackoverflow.com/questions/6139493/how-convert-char-to-int-in-linux-kernel/49811658#49811658
@@ -5751,7 +5751,7 @@ insmod /virt_to_phys.ko
 cat /sys/kernel/debug/lkmc_virt_to_phys
 ....
 
-Source: link:packages/lkmc/kernel_modules/virt_to_phys.c[]
+Source: link:kernel_modules/virt_to_phys.c[]
 
 Sample output:
 
@@ -5808,7 +5808,7 @@ First get a virtual address to play with:
 /virt_to_phys_test.out &
 ....
 
-Source: link:packages/lkmc/userland/virt_to_phys_test.c[]
+Source: link:userland/virt_to_phys_test.c[]
 
 Sample output:
 
@@ -5835,7 +5835,7 @@ Sample output physical address:
 0x7c7b800
 ....
 
-Source: link:packages/lkmc/userland/virt_to_phys_user.c[]
+Source: link:userland/virt_to_phys_user.c[]
 
 Now we can verify that `virt_to_phys_user.out` gave the correct physical address in the following ways:
 
@@ -5952,7 +5952,7 @@ vaddr pfn soft-dirty file/shared swapped present library
 7ffff78ec000 1fd4 0 1 0 1 /lib/libuClibc-1.0.30.so
 ....
 
-Source: link:packages/lkmc/userland/pagemap_dump.c[]
+Source: link:userland/pagemap_dump.c[]
 
 Adapted from: https://github.com/dwks/pagemap/blob/8a25747bc79d6080c8b94eac80807a4dceeda57a/pagemap2.c
 
@@ -6028,7 +6028,7 @@ I hope to have examples of all methods some day, since I'm obsessed with visibil
 
 ==== CONFIG_PROC_EVENTS
 
-Logs proc events such as process creation to a link:packages/lkmc/kernel_modules/netlink.c[netlink socket].
+Logs proc events such as process creation to a link:kernel_modules/netlink.c[netlink socket].
 
 We then have a userland program that listens to the events and prints them out:
 
@@ -6047,7 +6047,7 @@ a
 #
 ....
 
-Source: link:packages/lkmc/userland/proc_events.c[]
+Source: link:userland/proc_events.c[]
 
 TODO: why `exit: tid=79` shows after `exit: tid=80`?
 
@@ -6255,7 +6255,7 @@ Outcome: dmesg outputs on every fork:
 <_do_fork> post_handler: p->addr = 0x00000000e1360063, flags = 0x246
 ....
 
-Source: link:packages/lkmc/kernel_modules/kprobe_example.c[]
+Source: link:kernel_modules/kprobe_example.c[]
 
 TODO: it does not work if I try to immediately launch `sleep`, why?
 
@@ -6420,7 +6420,7 @@ TODO not always reproducible. Find a more reproducible failure. I could not obse
 insmod /memcpy_overflow.ko
 ....
 
-Source: link:packages/lkmc/kernel_modules/strlen_overflow.c[]
+Source: link:kernel_modules/strlen_overflow.c[]
 
 Bibliography: https://www.reddit.com/r/hacking/comments/8h4qxk/what_a_buffer_overflow_in_the_linux_kernel_looks/
 
@@ -6462,7 +6462,7 @@ UIO interface in a nutshell:
 
 Sources:
 
-* link:packages/lkmc/userland/uio_read.c[]
+* link:userland/uio_read.c[]
 * link:rootfs_overlay/uio_read.sh[]
 
 Bibliography:
@@ -6593,7 +6593,7 @@ Minimal example:
 ./run --kernel-cli 'init=/ctrl_alt_del.out' --graphic
 ....
 
-Source: link:packages/lkmc/userland/ctrl_alt_del.c[]
+Source: link:userland/ctrl_alt_del.c[]
 
 When you hit `Ctrl-Alt-Del` in the guest, our tiny init handles a `SIGINT` sent by the kernel and outputs to stdout:
 
@@ -6910,7 +6910,7 @@ DRM / DRI is the new interface that supersedes `fbdev`:
 ./run --eval-busybox '/libdrm_modeset.out' --graphic
 ....
 
-Source: link:packages/lkmc/userland/libdrm_modeset.c[]
+Source: link:userland/libdrm_modeset.c[]
 
 Outcome: for a few seconds, the screen that contains the terminal gets taken over by changing colors of the rainbow.
 
@@ -7316,7 +7316,7 @@ insmod /pci_min.ko
 
 Sources:
 
-* Kernel module: link:packages/lkmc/kernel_modules/pci_min.c[].
+* Kernel module: link:kernel_modules/pci_min.c[].
 * QEMU device: https://github.com/cirosantilli/qemu/blob/lkmc/hw/misc/lkmc_pci_min.c
 
 Outcome:
@@ -7355,7 +7355,7 @@ This tests a lot of features of the edu device, to understand the results, compa
 
 Sources:
 
-* kernel module: link:packages/lkmc/kernel_modules/qemu_edu.c[]
+* kernel module: link:kernel_modules/qemu_edu.c[]
 * QEMU device: https://github.com/qemu/qemu/blob/v2.12.0/hw/misc/edu.c
 * test script: link:rootfs_overlay/qemu_edu.sh[]
 
@@ -8684,7 +8684,7 @@ and then feed `bst_vs_heap.dat` into: https://github.com/cirosantilli/cpp-cheat/
 Sources:
 
 * link:bst-vs-heap[]
-* link:packages/lkmc/userland/bst_vs_heap.cpp[]
+* link:userland/bst_vs_heap.cpp[]
 
 ===== OpenMP
 
@@ -8694,7 +8694,7 @@ Implemented by GCC itself, so just a toolchain configuration, no external libs,
 /openmp.out
 ....
 
-Source: link:packages/lkmc/userland/openmp.c[]
+Source: link:userland/openmp.c[]
 
 ===== BLAS
 
@@ -8712,7 +8712,7 @@ Outcome: the test passes:
 0
 ....
 
-Source: link:packages/lkmc/userland/openblas.c[]
+Source: link:userland/openblas.c[]
 
 The test performs a general matrix multiplication:
 
@@ -8758,7 +8758,7 @@ Output:
 2.5 1.5
 ....
 
-Source: link:packages/lkmc/userland/eigen_hello.cpp[]
+Source: link:userland/eigen_hello.cpp[]
 
 This example just creates a matrix and prints it out.
 
@@ -9443,8 +9443,8 @@ The executable `/m5ops.out` illustrates how to hard code with inline assembly th
 
 Sources:
 
-* link:packages/lkmc/userland/m5ops.h[]
+* link:userland/m5ops.h[]
-* link:packages/lkmc/userland/m5ops.c[]
+* link:userland/m5ops.c[]
 
 That executable is of course a subset of <<m5>> and useless by itself: its goal is only illustrate how to hardcode some <<m5ops>> yourself as one-liners.
 
@@ -9592,7 +9592,7 @@ Let's have some fun and try to correlate the gem5 cycle count `system.cpu.numCyc
 ./gem5-stat
 ....
 
-Source: link:packages/lkmc/userland/rdtsc.c[]
+Source: link:userland/rdtsc.c[]
 
 `rdtsc` outputs a cycle count which we compare with gem5's `gem5-stat`:
 
@@ -9610,7 +9610,7 @@ Bibliography:
 
 ===== pmccntr
 
-TODO We didn't manage to find a working ARM analogue to <<rdtsc>>: link:packages/lkmc/kernel_modules/pmccntr.c[] is oopsing, and even it if weren't, it likely won't give the cycle count since boot since it needs to be activate before it starts counting anything:
+TODO We didn't manage to find a working ARM analogue to <<rdtsc>>: link:kernel_modules/pmccntr.c[] is oopsing, and even it if weren't, it likely won't give the cycle count since boot since it needs to be activate before it starts counting anything:
 
 * https://stackoverflow.com/questions/40454157/is-there-an-equivalent-instruction-to-rdtsc-in-arm
 * https://stackoverflow.com/questions/31620375/arm-cortex-a7-returning-pmccntr-0-in-kernel-mode-and-illegal-instruction-in-u/31649809#31649809
@@ -9798,7 +9798,7 @@ You will likely want to change that to:
 BR2_OPTIMIZE_3=y
 ....
 
-Our link:packages/lkmc/kernel_modules/user[] package correctly forwards the Buildroot options to the build with `$(TARGET_CONFIGURE_OPTS)`, so you don't have to do any extra work.
+Our link:kernel_modules/user[] package correctly forwards the Buildroot options to the build with `$(TARGET_CONFIGURE_OPTS)`, so you don't have to do any extra work.
 
 Don't forget to do that if you are <<add-new-buildroot-packages,adding a new package>> with your own build system.
 
@@ -9894,7 +9894,7 @@ with:
 
 First, see if you can't get away without actually adding a new package, for example:
 
-* if you have a standalone C file with no dependencies besides the C standard library to be compiled with GCC, just add a new file under link:packages/lkmc/kernel_modules/user[] and you are done
+* if you have a standalone C file with no dependencies besides the C standard library to be compiled with GCC, just add a new file under link:kernel_modules/user[] and you are done
 * if you have a dependency on a library, first check if Buildroot doesn't have a package for it already with `ls buildroot/package`. If yes, just enable that package as explained at: <<custom-buildroot-configs>>
 
 If none of those methods are flexible enough for you, you can just fork or hack up link:packages/sample_package[] the sample package to do what you want.
@@ -11084,6 +11084,12 @@ There is also the `m5` tool that we must build through Buildroot ans install on
 
 This directory has the following structure:
 
+==== include directory
+
+link:include/[] contains headers that are shared acros both kernel modules and userland structures.
+
+They contain data structs and magic constant for kernel to userland communication.
+
 ==== packages directory
 
 Every directory inside it is a Buildroot package.
@@ -11137,7 +11143,7 @@ We use it for:
 * customized configuration files
 * userland module test scripts that don't need to be compiled.
 +
-C files for example need compilation, and must go through the regular package system, e.g. through link:packages/lkmc/kernel_modules/user[].
+C files for example need compilation, and must go through the regular package system, e.g. through link:kernel_modules/user[].
 
 === Test this repo
 
@@ -11281,8 +11287,8 @@ hello cpp
 
 Sources:
 
-* link:packages/lkmc/userland/hello.c[]
+* link:userland/hello.c[]
-* link:packages/lkmc/userland/hello_cpp.c[]
+* link:userland/hello_cpp.c[]
 
 ==== rand_check.out
 
@@ -11292,7 +11298,7 @@ Print out several parameters that normally change randomly from boot to boot:
 ./run --eval-busybox '/rand_check.out;/poweroff.out'
 ....
 
-Source: link:packages/lkmc/userland/rand_check.c[]
+Source: link:userland/rand_check.c[]
 
 This can be used to check the determinism of:
 

build-modules

@@ -41,8 +41,13 @@ class ModulesComponent(common.Component):
         # This copies only modified files as per:
         # https://stackoverflow.com/questions/5718899/building-an-out-of-tree-linux-kernel-module-in-a-separate-object-directory
         distutils.dir_util.copy_tree(
-            common.lkmc_package_src_dir,
+            common.kernel_modules_src_dir,
-            os.path.join(build_dir),
+            os.path.join(build_dir, common.kernel_modules_subdir),
+            update=1,
+        )
+        distutils.dir_util.copy_tree(
+            common.include_src_dir,
+            os.path.join(build_dir, common.include_subdir),
             update=1,
         )
         all_kernel_modules = []

build-overlay

@@ -0,0 +1,73 @@
+
+#!/usr/bin/env python3
+
+import os
+import platform
+import shutil
+import subprocess
+
+import common
+
+class UserlandComponent(common.Component):
+    def add_parser_arguments(self, parser):
+        parser.add_argument(
+            '--has-package',
+            action='append',
+            default=[],
+            help='''\
+Indicate that a given package is present in the root filesystem, which
+allows us to build examples that rely on it.
+''',
+        )
+        parser.add_argument(
+            'targets',
+            default=[],
+            help='''\
+Build only the given userland programs.
+Default: build all examples that have their package dependencies met.
+For example, an OpenBLAS example can only be built if the target root filesystem
+has the OpenBLAS libraries and headers installed.
+''',
+            metavar='programs',
+            nargs='*',
+        )
+
+    def do_build(self, args):
+        build_dir = self.get_build_dir(args)
+        os.makedirs(build_dir, exist_ok=True)
+        allowed_toolchains = ['buildroot']
+        cc = common.get_toolchain_tool('gcc', allowed_toolchains=allowed_toolchains)
+        cxx = common.get_toolchain_tool('g++', allowed_toolchains=allowed_toolchains)
+        common.run_cmd(
+            (
+                [
+                    'make',
+                    '-j', str(args.nproc),
+                    'CC={}'.format(cc),
+                    'CXX={}'.format(cxx),
+                    'PKG_CONFIG={}'.format(common.buildroot_pkg_config),
+                    'STAGING_DIR={}'.format(common.buildroot_staging_dir),
+                    'OUT_DIR={}'.format(build_dir),
+                ] +
+                ['HAS_{}=y'.format(package.upper()) for package in args.has_package] +
+                [os.path.join(build_dir, os.path.splitext(os.path.split(target)[1])[0]) + common.executable_ext for target in args.targets]
+            ),
+            cwd=common.userland_src_dir,
+            extra_paths=[common.ccache_dir],
+        )
+        common.copy_dir_if_update_non_recursive(
+            srcdir=build_dir,
+            destdir=common.out_rootfs_overlay_dir,
+            filter_ext=common.executable_ext,
+        )
+
+    def get_argparse_args(self):
+        return {
+            'description': 'Build our compiled userland examples',
+        }
+
+    def get_build_dir(self, args):
+        return common.userland_build_dir
+
+if __name__ == '__main__':
+    UserlandComponent().build()

common.py

@@ -32,9 +32,11 @@ bench_boot = os.path.join(out_dir, 'bench-boot.txt')
 packages_dir = os.path.join(root_dir, 'packages')
 lkmc_package_src_dir = os.path.join(this_module.packages_dir, 'lkmc')
 kernel_modules_subdir = 'kernel_modules'
-kernel_modules_src_dir = os.path.join(this_module.lkmc_package_src_dir, this_module.kernel_modules_subdir)
+kernel_modules_src_dir = os.path.join(this_module.root_dir, this_module.kernel_modules_subdir)
 userland_subdir = 'userland'
-userland_src_dir = os.path.join(this_module.lkmc_package_src_dir, this_module.userland_subdir)
+userland_src_dir = os.path.join(this_module.root_dir, this_module.userland_subdir)
+include_subdir = 'include'
+include_src_dir = os.path.join(this_module.root_dir, this_module.include_subdir)
 submodules_dir = os.path.join(root_dir, 'submodules')
 buildroot_src_dir = os.path.join(submodules_dir, 'buildroot')
 crosstool_ng_src_dir = os.path.join(submodules_dir, 'crosstool-ng')

include/README.adoc

@@ -0,0 +1 @@
+https://github.com/cirosantilli/linux-kernel-module-cheat#include-directory

kernel_modules/anonymous_inode.c

@@ -9,7 +9,7 @@
 #include <linux/printk.h> /* printk */
 #include <linux/uaccess.h> /* copy_from_user */
 
-#include "../anonymous_inode.h"
+#include "../include/anonymous_inode.h"
 
 static struct dentry *debugfs_file;
 static u32 myval = 1;

kernel_modules/ioctl.c

@@ -5,7 +5,7 @@
 #include <linux/printk.h> /* printk */
 #include <linux/uaccess.h> /* copy_from_user, copy_to_user */
 
-#include "../ioctl.h"
+#include "../include/ioctl.h"
 
 static struct dentry *debugfs_file;
 

kernel_modules/netlink.c

@@ -6,7 +6,7 @@
 #include <linux/skbuff.h>
 #include <net/sock.h>
 
-#include "../netlink.h"
+#include "../include/netlink.h"
 
 struct sock *nl_sk = NULL;
 

kernel_modules/ring0.c

@@ -3,7 +3,7 @@
 #include <linux/module.h>
 #include <linux/kernel.h>
 
-#include "../ring0.h"
+#include "../include/ring0.h"
 
 static int myinit(void)
 {

packages/gem5/.gitignore

@@ -1 +0,0 @@
-/system

packages/gem5/Config.in

@@ -1,7 +0,0 @@
-config BR2_PACKAGE_GEM5
-	bool "gem5"
-	help
-	  Only for the m5 guest instrumentation tool of the gem5 system simulator,
-	  does not build the simulator itself.
-
-	  http://gem5.org

packages/gem5/README.adoc

@@ -1 +0,0 @@
-https://github.com/cirosantilli/linux-kernel-module-cheat#gem5-directory

packages/gem5/external.desc

@@ -1 +0,0 @@
-name: GEM5

packages/gem5/external.mk

@@ -1,27 +0,0 @@
-################################################################################
-#
-# GEM5
-#
-################################################################################
-
-GEM5_VERSION = 1.0
-GEM5_SITE = $(LKMC_GEM5_SRCDIR)
-GEM5_SITE_METHOD = local
-
-ifeq ($(ARCH),x86_64)
-ARCH_MAKE = x86
-else
-ARCH_MAKE = $(ARCH)
-endif
-
-define GEM5_BUILD_CMDS
-	# TODO cannot use TARGET_CONFIGURE_OPTS here because it overrides the CFLAGS on m5,
-	# which have an include. We should patch gem5 to add a += instead of = there.
-	cd '$(@D)/util/m5' && $(MAKE) -f 'Makefile.$(ARCH_MAKE)' CC='$(TARGET_CC)' LD='$(TARGET_LD)'
-endef
-
-define GEM5_INSTALL_TARGET_CMDS
-	$(INSTALL) -D -m 0755 '$(@D)/util/m5/m5' '$(TARGET_DIR)/usr/bin'
-endef
-
-$(eval $(generic-package))

packages/lkmc/Config.in

@@ -1,5 +0,0 @@
-config BR2_PACKAGE_LKMC
-	bool "lkmc"
-	depends on BR2_LINUX_KERNEL
-	help
-		Linux Kernel Module Cheat kernel modules and compiled userland examples.

packages/lkmc/README.adoc

@@ -1 +0,0 @@
-https://github.com/cirosantilli/linux-kernel-module-cheat#directory-structure

packages/lkmc/external.desc

@@ -1 +0,0 @@
-name: LKMC

packages/lkmc/external.mk

@@ -1,40 +0,0 @@
-################################################################################
-#
-# kernel_modules
-#
-################################################################################
-
-LKMC_VERSION = 1.0
-LKMC_SITE = $(BR2_EXTERNAL_LKMC_PATH)
-LKMC_SITE_METHOD = local
-LKMC_MODULE_SUBDIRS = kernel_modules
-
-ifeq ($(BR2_PACKAGE_EIGEN),y)
-	LKMC_DEPENDENCIES += eigen
-endif
-ifeq ($(BR2_PACKAGE_LIBDRM),y)
-	LKMC_DEPENDENCIES += libdrm
-endif
-ifeq ($(BR2_PACKAGE_OPENBLAS),y)
-	LKMC_DEPENDENCIES += openblas
-endif
-
-define LKMC_BUILD_CMDS
-	$(MAKE) -C '$(@D)/userland' $(TARGET_CONFIGURE_OPTS) \
-	  HAS_EIGEN="$(BR2_PACKAGE_EIGEN)" \
-	  HAS_LIBDRM="$(BR2_PACKAGE_LIBDRM)" \
-	  HAS_OPENBLAS="$(BR2_PACKAGE_OPENBLAS)" \
-	;
-endef
-
-define LKMC_INSTALL_TARGET_CMDS
-	# The modules are already installed by the kernel-module package type
-	# under /lib/modules/**, but let's also copy the modules to the root
-	# for insmod convenience.
-	#
-	# Modules can be still be easily inserted with "modprobe module" however.
-	$(INSTALL) -D -m 0755 $(@D)/userland/*.out '$(TARGET_DIR)'
-endef
-
-$(eval $(kernel-module))
-$(eval $(generic-package))

userland/anonymous_inode.c

@@ -10,7 +10,7 @@
 #include <sys/types.h>
 #include <unistd.h> /* sleep */
 
-#include "../anonymous_inode.h"
+#include "../include/anonymous_inode.h"
 
 int main(int argc, char **argv)
 {

userland/ioctl.c

@@ -10,7 +10,7 @@
 #include <sys/types.h>
 #include <unistd.h>
 
-#include "../ioctl.h"
+#include "../include/ioctl.h"
 
 int main(int argc, char **argv)
 {

userland/netlink.c

@@ -7,7 +7,7 @@
 #include <sys/socket.h>
 #include <unistd.h>
 
-#include "../netlink.h"
+#include "../include/netlink.h"
 
 #define MAX_PAYLOAD 1024
 

userland/ring0.c

@@ -3,7 +3,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-#include "../ring0.h"
+#include "../include/ring0.h"
 
 int main(void) {
 #if defined(__x86_64__) || defined(__i386__)