2.Linux移植项目

mizi-linux已经根据Linux 2.4内核针对S3C2410A这一芯片进行了有针对性的移植工作，包括：

（1）修改根目录下的Makefile文件

a.指定目标平台为ARM：

#ARCH := $(shell uname -m | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ -e s/arm.*/arm/ -e s/sa110/arm/)

ARCH := arm

b.指定交叉编译器：

CROSS_COMPILE = arm-linux-

（2）修改arch目录中的文件

根据本章第一节可知，Linux的arch目录存放硬件相关的内核代码，因此，在Linux内核中增加对S3C2410的支持，最主要就是要修改arch目录中的文件。

a.在arch/arm/Makefile文件中加入：

ifeq ($(CONFIG_ARCH_S3C2410),y)

TEXTADDR = 0xC0008000

MACHINE = s3c2410

Endif

b.在arch\arm\config.in文件中加入：

if [ "$CONFIG_ARCH_S3C2410" = "y" ]; then

comment 'S3C2410 Implementation'

dep_bool ' SMDK (MERI TECH BOARD)' CONFIG_S3C2410_SMDK $CONFIG_ARCH_S3C2410

dep_bool ' change AIJI' CONFIG_SMDK_AIJI

dep_tristate 'S3C2410 USB function support' CONFIG_S3C2410_USB $CONFIG_ARCH_S3C2100

dep_tristate ' Support for S3C2410 USB character device emulation' CONFIG_S3C2410_USB_CHAR $CONFIG_S3C2410_USB

fi # /* CONFIG_ARCH_S3C2410 */

arch\arm\config.in文件还有几处针对S3C2410的修改。

c.在arch/arm/boot/Makefile文件中加入：

ifeq ($(CONFIG_ARCH_S3C2410),y)

ZTEXTADDR = 0x30008000

ZRELADDR = 0x30008000

endif

d.在linux/arch/arm/boot/compressed/Makefile文件中加入：

ifeq ($(CONFIG_ARCH_S3C2410),y)

OBJS += head-s3c2410.o

endif

加入的结果是head-s3c2410.S文件被编译为head-s3c2410.o。

e.加入arch\arm\boot\compressed\ head-s3c2410.S文件

#include

#include

#include

.section ".start", #alloc, #execinstr

__S3C2410_start:

@ Preserve r8/r7 i.e. kernel entry values

@ What is it?

@ Nandy

@ Data cache, Intstruction cache, MMU might be active.

@ Be sure to flush kernel binary out of the cache,

@ whatever state it is, before it is turned off.

@ This is done by fetching through currently executed

@ memory to be sure we hit the same cache

bic r2, pc, #0x1f

add r3, r2, #0x4000 @ 16 kb is quite enough...

1: ldr r0, [r2], #32

teq r2, r3

bne 1b

mcr p15, 0, r0, c7, c10, 4 @ drain WB

mcr p15, 0, r0, c7, c7, 0 @ flush I & D caches

#if 0

@ disabling MMU and caches

mrc p15, 0, r0, c1, c0, 0 @ read control register

bic r0, r0, #0x05 @ disable D cache and MMU

bic r0, r0, #1000 @ disable I cache

mcr p15, 0, r0, c1, c0, 0

#endif

/*

* Pause for a short time so that we give enough time

* for the host to start a terminal up.

*/

mov r0, #0x00200000

1: subs r0, r0, #1

bne 1b

该文件中的汇编代码完成S3C2410特定硬件相关的初始化。

f.在arch\arm\def-configs目录中增加配置文件

g.在arch\arm\kernel\Makefile中增加对S3C2410的支持

no-irq-arch := $(CONFIG_ARCH_INTEGRATOR) $(CONFIG_ARCH_CLPS711X) \

$(CONFIG_FOOTBRIDGE) $(CONFIG_ARCH_EBSA110) \

$(CONFIG_ARCH_SA1100) $(CONFIG_ARCH_CAMELOT) \

$(CONFIG_ARCH_S3C2400) $(CONFIG_ARCH_S3C2410) \

$(CONFIG_ARCH_MX1ADS) $(CONFIG_ARCH_PXA)

obj-$(CONFIG_MIZI) += event.o

obj-$(CONFIG_APM) += apm2.o

h.修改arch/arm/kernel/debug-armv.S文件，在适当的位置增加如下关于S3C2410的代码：

#elif defined(CONFIG_ARCH_S3C2410)

.macro addruart,rx

mrc p15, 0, \rx, c1, c0

tst \rx, #1 @ MMU enabled ?

moveq \rx, #0x50000000 @ physical base address

movne \rx, #0xf0000000 @ virtual address

.endm

.macro senduart,rd,rx

str \rd, [\rx, #0x20] @ UTXH

.endm

.macro waituart,rd,rx

.endm

.macro busyuart,rd,rx

1001: ldr \rd, [\rx, #0x10] @ read UTRSTAT

tst \rd, #1 << 2 @ TX_EMPTY ?

beq 1001b

.endm

i.修改arch/arm/kernel/setup.c文件

此文件中的setup_arch非常关键，用来完成与体系结构相关的初始化：

void __init setup_arch(char **cmdline_p)

{

struct tag *tags = NULL;

struct machine_desc *mdesc;

char *from = default_command_line;

ROOT_DEV = MKDEV(0, 255);

setup_processor();

mdesc = setup_machine(machine_arch_type);

machine_name = mdesc->name;

if (mdesc->soft_reboot)

reboot_setup("s");

if (mdesc->param_offset)

tags = phys_to_virt(mdesc->param_offset);

/*

* Do the machine-specific fixups before we parse the

* parameters or tags.

*/

if (mdesc->fixup)

mdesc->fixup(mdesc, (struct param_struct *)tags,

&from, &meminfo);

/*

* If we have the old style parameters, convert them to

* a tag list before.

*/

if (tags && tags->hdr.tag != ATAG_CORE)

convert_to_tag_list((struct param_struct *)tags,

meminfo.nr_banks == 0);

if (tags && tags->hdr.tag == ATAG_CORE)

parse_tags(tags);

if (meminfo.nr_banks == 0) {

meminfo.nr_banks = 1;

meminfo.bank[0].start = PHYS_OFFSET;

meminfo.bank[0].size = MEM_SIZE;

}

init_mm.start_code = (unsigned long) &_text;

init_mm.end_code = (unsigned long) &_etext;

init_mm.end_data = (unsigned long) &_edata;

init_mm.brk = (unsigned long) &_end;

memcpy(saved_command_line, from, COMMAND_LINE_SIZE);

saved_command_line[COMMAND_LINE_SIZE-1] = '\0';

parse_cmdline(&meminfo, cmdline_p, from);

bootmem_init(&meminfo);

paging_init(&meminfo, mdesc);

request_standard_resources(&meminfo, mdesc);

/*

* Set up various architecture-specific pointers

*/

init_arch_irq = mdesc->init_irq;

#ifdef CONFIG_VT

#if defined(CONFIG_VGA_CONSOLE)

conswitchp = &vga_con;

#elif defined(CONFIG_DUMMY_CONSOLE)

conswitchp = &dummy_con;

#endif

#endif

}

j.修改arch/arm/mm/mm-armv.c文件（arch/arm/mm/目录中的文件完成与ARM相关的MMU处理）

修改

init_maps->bufferable = 0;

为

init_maps->bufferable = 1;