pci negator working, factorial not

rootfs_overlay/README.md

@@ -0,0 +1,8 @@
+# rootfs_overlay
+
+This directory copied into the target filesystem.
+
+We use it to for things like:
+
+- customized configuration files
+- userland module test scripts

rootfs_overlay/character_device.sh

@@ -1,7 +1,7 @@
 #!/bin/sh
 insmod /character_device.ko
-major="$(grep lkmc_character_device /proc/devices | cut -d ' ' -f 1)"
-mknod /character_device.dev c $major 0
-cat /character_device.dev
+/mknoddev.sh character_device
+cat /dev/lkmc_character_device
 # => abcd
+rm /dev/lkmc_character_device
 rmmod character_device

rootfs_overlay/mknoddev.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+dev="lkmc_$1"
+major="$(grep "$dev" /proc/devices | cut -d ' ' -f 1)"
+mknod "/dev/$dev" c "$major" 0

rootfs_overlay/pci.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+
+set -ex
+
+# Setup.
+insmod /pci.ko
+/mknoddev.sh pci
+
+# Identifiction.
+dd bs=4 status=none if=/dev/lkmc_pci count=1 skip=0 | od -An -t x1
+# => 010000ed
+
+# Negator.
+dd bs=4 status=none if=/dev/lkmc_pci count=1 skip=1 | od -An -t x1
+printf '\xF0\xF0\xF0\xF0' | dd bs=4 status=none of=/dev/lkmc_pci count=1 seek=1
+dd bs=4 status=none if=/dev/lkmc_pci count=1 skip=1 | od -An -t x1
+# => 0F0F0F0F
+
+# Factorial calculator.
+# factorial(0xC) = 0x1c8cfc00
+printf '\x00\x00\x00\x0C' | dd bs=4 status=none of=/dev/lkmc_pci count=1 seek=2
+printf '\x00\x00\x00\x00' | dd bs=4 status=none of=/dev/lkmc_pci count=1 seek=8
+sleep 1
+dd bs=4 status=none if=/dev/lkmc_pci count=1 skip=2 | od -An -t x1
+dd bs=4 status=none if=/dev/lkmc_pci count=1 skip=8 | od -An -t x1
+# => 1c8cfc00
+
+# Teardown.
+rm /dev/lkmc_pci
+rmmod pci