内核中的关键地址

原文：

 

1）TEXT_OFFSET  内核在RAM中的起始位置相对于RAM起始地址偏移。值为0x00008000

./arch/arm/Makefile
111 textofs-y := 0x00008000
112 textofs-$(CONFIG_ARCH_CLPS711X) := 0x00028000
113 # We don't want the htc bootloader to corrupt kernel during resume
114 textofs-$(CONFIG_PM_H1940) := 0x00108000
115 # SA1111 DMA bug: we don't want the kernel to live in precious DMA-able memory
116 ifeq ($(CONFIG_ARCH_SA1100),y)
117 textofs-$(CONFIG_SA1111) := 0x00208000
118 endif

212 # The byte offset of the kernel image in RAM from the start of RAM.
213 TEXT_OFFSET := $(textofs-y)

2）PAGE_OFFSE   内核镜像起始虚拟地址。值为0xC0000000

arch/arm/Kconfig
1165 config PAGE_OFFSET ----这个就是CONFIG_PAGE_OFFSET宏，默认值为0xC0000000
1166 hex
1167 default 0x40000000 if VMSPLIT_1G
1168 default 0x80000000 if VMSPLIT_2G
1169 default 0xC0000000

./arch/arm/include/asm/memory.h
34 #define PAGE_OFFSET UL(CONFIG_PAGE_OFFSET)

3）PHYS_OFFSET  RAM启始物理地址，对应于DDR的物理地址。需要在mach-xxxx/include/mach/memory.h文件中定义这个宏。

 

对于2410来说值为0x30000000，RAM接在片选6上
arch/arm/mach-s3c2410/include/mach/memory.h
#define PHYS_OFFSET    UL(0x30000000)

4）KERNEL_RAM_VADDR  内核在RAM中的虚拟地址。值为0xC0008000
5）KERNEL_RAM_PADDR  内核在RAM中的物理地址。值为0x30008000

arch/arm/kernel/head.S
 29 #define KERNEL_RAM_VADDR        (PAGE_OFFSET + TEXT_OFFSET)
 30 #define KERNEL_RAM_PADDR        (PHYS_OFFSET + TEXT_OFFSET)

6）swapper_pg_dir 初始页表虚拟地址，值为0xC0004000，

一般分配KERNEL_RAM_VADDR地址下16K作为页表，因此，我们必须确保正确设置KERNEL_RAM_VADDR。
arch/arm/kernel/head.S
 44         .globl  swapper_pg_dir
 45         .equ    swapper_pg_dir, KERNEL_RAM_VADDR - 0x4000

7）VMALLOC_START 0xc4800000
8）VMALLOC_END   0xe0000000

9）MODULES_VADDR 0xbf000000
10）MODULES_END   0xc0000000

 47 #ifndef CONFIG_THUMB2_KERNEL
 48 #define MODULES_VADDR           (PAGE_OFFSET - 16*1024*1024)
 49 #else
 50 /* smaller range for Thumb-2 symbols relocation (2^24)*/
 51 #define MODULES_VADDR           (PAGE_OFFSET - 8*1024*1024)
 52 #endif
 53 
 54 #if TASK_SIZE > MODULES_VADDR
 55 #error Top of user space clashes with start of module space
 56 #endif
 57 
 58 /*
 59  * The highmem pkmap virtual space shares the end of the module area.
 60  */
 61 #ifdef CONFIG_HIGHMEM
 62 #define MODULES_END             (PAGE_OFFSET - PMD_SIZE)
 63 #else
 64 #define MODULES_END             (PAGE_OFFSET)
 65 #endif

11)PKMAP_BASE          
arch/arm/include/asm/highmem.h:

6:#define PKMAP_BASE           (PAGE_OFFSET - PMD_SIZE)

 

12)TASK_SIZE
./arch/arm/include/asm/memory.h
 34 #define PAGE_OFFSET             UL(CONFIG_PAGE_OFFSET)
 35 #define TASK_SIZE               (UL(CONFIG_PAGE_OFFSET) - UL(0x01000000))
 36 #define TASK_UNMAPPED_BASE      (UL(CONFIG_PAGE_OFFSET) / 3)

13）一些不同地址之间转换的宏

./arch/arm/include/asm/memory.h

135 /*
136  * Physical vs virtual RAM address space conversion.  These are
137  * private definitions which should NOT be used outside memory.h
138  * files.  Use virt_to_phys/phys_to_virt/__pa/__va instead.
139  */
140 #ifndef __virt_to_phys
141 #define __virt_to_phys(x)       ((x) - PAGE_OFFSET + PHYS_OFFSET)//物理地址和虚拟地址
142 #define __phys_to_virt(x)       ((x) - PHYS_OFFSET + PAGE_OFFSET)//之间转换的宏
143 #endif
144
145 /*
146  * Convert a physical address to a Page Frame Number and back
147  */
148 #define __phys_to_pfn(paddr)    ((paddr) >> PAGE_SHIFT) //物理地址和页帧号之间
149 #define __pfn_to_phys(pfn)      ((pfn) << PAGE_SHIFT)   //转换的宏
150
151 /*
152  * Convert a page to/from a physical address
153  */
154 #define page_to_phys(page)      (__pfn_to_phys(page_to_pfn(page)))//页地址和物理地址
155 #define phys_to_page(phys)      (pfn_to_page(__phys_to_pfn(phys)))//之间的转换宏依赖于内存模型。

201 /*
202  * Drivers should NOT use these either.
203  */
204 #define __pa(x)                 __virt_to_phys((unsigned long)(x))
205 #define __va(x)                 ((void *)__phys_to_virt((unsigned long)(x)))
206 #define pfn_to_kaddr(pfn)       __va((pfn) << PAGE_SHIFT)
207

208 /*
209  * Virtual <-> DMA view memory address translations
210  * Again, these are *only* valid on the kernel direct mapped RAM
211  * memory.  Use of these is *deprecated* (and that doesn't mean
212  * use the __ prefixed forms instead.)  See dma-mapping.h.
213  */
214 #ifndef __virt_to_bus
215 #define __virt_to_bus   __virt_to_phys
216 #define __bus_to_virt   __phys_to_virt
217 #define __pfn_to_bus(x) __pfn_to_phys(x)
218 #define __bus_to_pfn(x) __phys_to_pfn(x)
219 #endif