フラッシュROMの空いているところにνカーネルを書き込む。

• 初期状態

# for i in 0 1 2 3 4
do
mknod /dev/fl$i b 250 $i
done
# ls -la /dev/fl*
brw-r--r--    1 root     root     250,   0 Jan  5  2005 /dev/fl0
brw-r--r--    1 root     root     250,   1 Jan  5  2005 /dev/fl1
brw-r--r--    1 root     root     250,   2 Jan  5  2005 /dev/fl2
brw-r--r--    1 root     root     250,   3 Jan  5  2005 /dev/fl3
brw-r--r--    1 root     root     250,   4 Jan  5  2005 /dev/fl4

# for i in 0 1 2 3 4
do
mknod /dev/mtd$i c 90 $( (i*2))
done
# for i in 0 1 2 3 4 5
do
mknod /dev/mtdblock$i b 31 $i
done
# ls -la /dev/mtd*
crw-r--r--    1 root     root      90,   0 Jul 31  2005 /dev/mtd0
crw-r--r--    1 root     root      90,   2 Jul 31  2005 /dev/mtd1
crw-r--r--    1 root     root      90,   4 Jul 31  2005 /dev/mtd2
crw-r--r--    1 root     root      90,   6 Jul 31  2005 /dev/mtd3
crw-r--r--    1 root     root      90,   8 Jul 31  2005 /dev/mtd4
brw-r--r--    1 root     root      31,   0 Jul 31  2005 /dev/mtdblock0
brw-r--r--    1 root     root      31,   1 Jul 31  2005 /dev/mtdblock1
brw-r--r--    1 root     root      31,   2 Jul 31  2005 /dev/mtdblock2
brw-r--r--    1 root     root      31,   3 Jul 31  2005 /dev/mtdblock3
brw-r--r--    1 root     root      31,   4 Jul 31  2005 /dev/mtdblock4
brw-r--r--    1 root     root      31,   5 Aug 16  2005 /dev/mtdblock5

• nkfd.o

nkfd.oによって0x00310000-0x00370000(fl2の後ろ),0x00380000-0x00400000(fl0)が /dev/nkfdに見えるようになる。

ブートコードとnkfd.oのコンパイル

パッチを当てる

$ tar zxvf linux-2.4.17_mvl21-sandpoint_040729.tar.gz
$ cd linux-2.4.17_mvl21-sandpoint
$ bzip2 -dc ../linux-2.4.17_mvl21-nbootcode-20050205.patch.bz2 | patch -p1

クロスコンパイル

$ vi .hhl_cross_compile
powerpc-linux-

make

$ make hdhglan_config
$ make oldconfig
$ make dep
$ make bootcode
$ ls arch/ppc/boot/images/
Makefile  bootcode.bin
$ make modules
$ ls ./drivers/block/flashdisk/nkfd.o
./drivers/block/flashdisk/nkfd.o

/dev/fl2 or /dev/mtdblock1 にνブートコードを書き込む

# dd if=nbootcode_hdhglan.bin of=/dev/mtdblock1

デバイスノードの作成

/dev/nkfdを作成してnkfd.oを読み込む

# mknod /dev/nkfd b 251 0
# insmod nkfd.o

確認

# dd if=/dev/nkfd of=nkfd.bin
# cat /dev/fl2 /dev/fl0 | tail -c 917504 - > fl2_0
# cmp fl2_0 nkfd.bin

νカーネル書き込み

kernimg.binを取り出す

# /root/bin/chkheader fl1.orig
info_ver:       0x00000001
firmid:         0x00001001
firmname:       KURO-BOX(IETSUNA)
subver:         FLASH 1.1
version:        major 0x0001 minor 0x0002
build:          0x0000
year/mon/day:   2004/04/16
hour:min:sec:   11:46:41
size:           2847034 (0x002b713a) bytes
chksum:         0x4c206901
kernel_offset:      108 (0x0000006c) bytes
kernel_size:     719495 (0x000afa87) bytes
initrd_offset:   719603 (0x000afaf3) bytes
initrd_size:    2127431 (0x00207647) bytes

checksum OK!
# head -c 719603 fl1.orig > kernimg.bin
# dd if=kernimg.bin of=/dev/nkfd

νカーネルの起動

/dev/fl3 の先頭から256byteのところに'LOAD'と書き込む

# head -c 256 /dev/fl3 | sed "s/\$/LOAD/" > /dev/fl3

ソースの修正

今までのkernimg.binがそのまま使えるようにする。'nkernel'と入力するとνカーネルを起動する。

$ diff -u arch/ppc/boot/common/misc-simple.c{.orig,}
--- arch/ppc/boot/common/misc-simple.c.orig     2005-08-13 05:02:26.000000000 +0900
+++ arch/ppc/boot/common/misc-simple.c  2005-08-13 08:43:01.441271157 +0900
@@ -163,6 +163,8 @@
 set_image(struct firminfo *info, int chkinitrd)
 {
     int i = 0;
+       int kern1size = 0x5ff94;
+       int nkfd2offset = 0x70000;

     _printk("\n******* Product Information *******\n");
     _printk("----------------------------------\n");
@@ -214,9 +216,9 @@

     if (info == (struct firminfo *)NKERNEL_IMAGE_ADDRESS) {
        zimage_start = (char *)NKERNEL_CONCAT_ADDRESS;
-       memcpy(zimage_start, (char *)info + info->kernel_offset, info->kernel_size);
-       memcpy(zimage_start + info->kernel_size, (char *)info + info->initrd_offset, info->initrd_size);
-       zimage_size = info->kernel_size + info->initrd_size;
+       memcpy(zimage_start, (char *)info + info->kernel_offset, kern1size);
+       memcpy(zimage_start + kern1size, (char *)info + nkfd2offset, info->kernel_size - kern1size);
+       zimage_size  = (int)info->kernel_size;
        info = image_addr;
     } else {
        if (checksum_check((unsigned char*)info,info->size) != 0) {
@@ -345,6 +347,7 @@
        }

        _printk("call set_image(%08x, %d)\n", info, chkinitrd);
+force_nkernel:
        force_dbg += set_image(info, chkinitrd);
 #else  /* FLASH_BOOT_IMAGE */
        /* we have to subtract 0x10000 here to correct for objdump including
@@ -476,6 +479,12 @@
            memcpy (cmd_line, cmd_preset, sizeof(cmd_preset));
            dbg_mode();
        }
+       i=0;while(i<7 && cmd_line[i] == "nkernel"[i]) ++i;
+       if (i > 6) {
+               info = (struct firminfo *)NKERNEL_IMAGE_ADDRESS;
+               chkinitrd = 1;
+               goto force_nkernel;
+       }
 #endif /* FLASH_BOOT_IMAGE */

        /* mappings on early boot can only handle 16M */

kernel2.4.20用のnkfd.oの作成

drivers/block/flashdisk/nkfd.cとinclude/melco/flashdisk.hをコピーする

$ mkdir nkfd
$ cd nkfd/
$ ls
flashdisk.h  nkfd.c

Makefileの作成

$ vi Makefile
CFLAGS = -Wall -O2 -DMODULE -D__KERNEL__
INCLUDE = -isystem /usr/src/linux/include/

nkfd.o:
    gcc -c $(CFLAGS) $(INCLUDE) nkfd.c
clean:
    rm -f nkfd.o

カーネルソースの展開

$ ls -l /usr/src/linux
lrwxrwxrwx    1 root     root           38 Aug  9 01:44
/usr/src/linux -> /mnt/kernel/linux-2.4.20_my02_hdhglan/
$ ls -l /usr/src/linux/include/asm
lrwxrwxrwx    1 afres    afres           7 Aug  9 01:34
/usr/src/linux/include/asm -> asm-ppc/