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--- etc:users:jcmvbkbc:little-things:1 [2009/12/22 12:09] – jcmvbkbc
+++ etc:users:jcmvbkbc:little-things:1 [2016/08/08 20:53] (current) – ↷ Page moved from users:jcmvbkbc:little-things:1 to etc:users:jcmvbkbc:little-things:1 kel
@@ Line 7: / Line 7: @@
 ===== Worklog =====
-  TBD
+  * get your future rootfs: build this directory tree, put busybox for i386 into bin, make symlinks to it, copy device nodes from system /dev
+<code>
+├── bin/
+│   ├── busybox*
+│   ├── cat -> busybox*
+│   ├── df -> busybox*
+│   ├── du -> busybox*
+│   ├── insmod -> busybox*
+│   ├── less -> busybox*
+│   ├── ln -> busybox*
+│   ├── ls -> busybox*
+│   ├── lsmod -> busybox*
+│   ├── mount -> busybox*
+│   ├── rmmod -> busybox*
+│   ├── sh -> busybox*
+│   ├── top -> busybox*
+│   └── vi -> busybox*
+├── dev/
+│   ├── pts/
+│   ├── console
+│   ├── kmsg
+│   ├── loop0
+│   ├── loop1
+│   ├── loop2
+│   ├── loop3
+│   ├── loop4
+│   ├── loop5
+│   ├── loop6
+│   ├── loop7
+│   ├── mem
+│   ├── null
+│   ├── ptmx
+│   ├── random
+│   ├── systty
+│   ├── tty
+│   ├── tty0
+│   ├── tty1
+│   ├── tty2
+│   ├── urandom
+│   └── zero
+├── lib/
+│   └── modules/
+│       └── 2.6.33-rc1/
+├── proc/
+├── sbin/
+├── sys/
+├── tmp/
+├── init*
+└── test.ko
+</code>
+  * make /init like this:
+<file>
+#! /bin/sh
+mount -t proc proc /proc
+mount -t sysfs sysfs /sys
+mount -t devpts devpts /dev/pts
+while :
+do
+  /bin/sh
+done
+</file>
+  * get a linux, configure and compile it:
+<code>
+git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
+make ARCH=i386 defconfig
+# turn off networking as we don't need it
+# turn on initramfs:
+# General setup --->
+#   [*] Initial RAM filesystem and RAM disk (initramfs/initrd) support
+#   (/home/dumb/ws/ii/games-build/games/src/lkm/rootfs) Initramfs source file(s)
+make ARCH=i386 menuconfig
+make ARCH=i386 -j3 bzImage
+</code>
+  * make test.c, module source:
+<file>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+static irqreturn_t test_irq_handler(int i, void *dev)
+{
+    static spinlock_t lock = __SPIN_LOCK_UNLOCKED(lock);
+    unsigned long flags;
+    printk(KERN_INFO "%s(%d, %p)\n", __func__, i, dev);
+    spin_lock_irqsave(&lock, flags);
+    printk(KERN_INFO "flags: %lx\n", flags);
+    spin_unlock_irqrestore(&lock, flags);
+    return IRQ_HANDLED;
+}
+static int test_irq;
+static int test_irq_no;
+#define IRQ_NO test_irq_no
+module_param(test_irq_no, int, 13);
+MODULE_PARM_DESC(test_irq_no, "requested IRQ line");
+static int __init test_init(void)
+{
+        int rc;
+        printk(KERN_INFO "%s\n", __func__);
+        rc = request_irq(IRQ_NO, test_irq_handler, IRQF_SHARED, "test_device", &test_irq);
+        printk(KERN_INFO "request_irq(%d, %p): %d\n", IRQ_NO, &test_irq, rc);
+        if (!rc)
+            test_irq = IRQ_NO;
+        return 0;
+}
+static void __exit test_exit(void)
+{
+        printk(KERN_INFO "%s\n", __func__);
+        if (test_irq)
+            free_irq(test_irq, &test_irq);
+}
+module_init(test_init);
+module_exit(test_exit);
+MODULE_AUTHOR("jcmvbkbc");
+MODULE_LICENSE("GPL");
+</file>
+  * make a Makefile for it:
+<code>
+PWD = $(shell pwd)
+EXTRA_CFLAGS += -Wall
+obj-m += test.o
+default: modules
+modules clean:
+        make -C $(KDIR) M=$(PWD) $@
+</code>
+  * compile it like this: make -C "$PWD/linux-2.6" ARCH=i386 M="$PWD" modules
+  * copy test.ko to the rootfs / and rebuild bzImage
+  * run it in qemu: qemu -kernel bzImage
+  * load module inside the shell in qemu: insmod test.ko test_irq_no=1
+  * press and release keys (irq 1 is keyboard interrupt)
+  * see it there: cat /proc/interrupts
+  * unload it: rmmod test
+Code: ftp://kkv.spb.su/pub/home/dumb/ws/lted/20091221/
 ===== Conclusion =====