uclinux-2008R1.5-RC3(bf561)到VDSP5的移植(52)：__ebss_l1

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ADI bf561 DSP

优视BF561EVB开发板

uclinux-2008r1.5-rc3(smp patch)

Visual DSP++ 5.0(update 5)

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有一个链接错误：

[Error li1021] The following symbols referenced in processor 'p0' could not be resolved:

'_ebss_l1 [__ebss_l1]' referenced from 'arch-kernel.dlb[setup.doj]'

'_sdata_l1 [__sdata_l1]' referenced from 'arch-kernel.dlb[setup.doj]'

引发这个链接错误的原因在setup_arch函数的末尾，有这样的语句：

/* Copy atomic sequences to their fixed location, and sanity check that

these locations are the ones that we advertise to userspace. */

memcpy((void *)FIXED_CODE_START, &fixed_code_start,

FIXED_CODE_END - FIXED_CODE_START);

BUG_ON((char *)&sigreturn_stub - (char *)&fixed_code_start

!= SIGRETURN_STUB - FIXED_CODE_START);

BUG_ON((char *)&atomic_xchg32 - (char *)&fixed_code_start

!= ATOMIC_XCHG32 - FIXED_CODE_START);

BUG_ON((char *)&atomic_cas32 - (char *)&fixed_code_start

!= ATOMIC_CAS32 - FIXED_CODE_START);

BUG_ON((char *)&atomic_add32 - (char *)&fixed_code_start

!= ATOMIC_ADD32 - FIXED_CODE_START);

BUG_ON((char *)&atomic_sub32 - (char *)&fixed_code_start

!= ATOMIC_SUB32 - FIXED_CODE_START);

BUG_ON((char *)&atomic_ior32 - (char *)&fixed_code_start

!= ATOMIC_IOR32 - FIXED_CODE_START);

BUG_ON((char *)&atomic_and32 - (char *)&fixed_code_start

!= ATOMIC_AND32 - FIXED_CODE_START);

BUG_ON((char *)&atomic_xor32 - (char *)&fixed_code_start

!= ATOMIC_XOR32 - FIXED_CODE_START);

BUG_ON((char *)&safe_user_instruction - (char *)&fixed_code_start

!= SAFE_USER_INSTRUCTION - FIXED_CODE_START);

在这里，FIXED_CODE_START等几个定义都在include/asm/fixed_code.h中：

///* This file defines the fixed addresses where userspace programs can find

// atomic code sequences. */

//

#define FIXED_CODE_START 0x400

//

#define SIGRETURN_STUB 0x400

//

#define ATOMIC_SEQS_START 0x410

//

#define ATOMIC_XCHG32 0x410

#define ATOMIC_CAS32 0x420

#define ATOMIC_ADD32 0x430

#define ATOMIC_SUB32 0x440

#define ATOMIC_IOR32 0x450

#define ATOMIC_AND32 0x460

#define ATOMIC_XOR32 0x470

//

#define ATOMIC_SEQS_END 0x480

//

#define SAFE_USER_INSTRUCTION 0x480

//

#define FIXED_CODE_END 0x490

//

而fixed_code_start则是arch/ blackfin/ kernel/fixed_code.s中定义的一个符号。在fixed_code.s中有一段说明：

/*

* This file contains sequences of code that will be copied to a

* fixed location, defined in <asm/atomic_seq.h>. The interrupt

* handlers ensure that these sequences appear to be atomic when

* executed from userspace.

* These are aligned to 16 bytes, so that we have some space to replace

* these sequences with something else (e.g. kernel traps if we ever do

* BF561 SMP).

*/

但是实在不明白为什么要将这些代码复制到这个固定的位置？？

这段代码引发的__ebss_l1符号链接错误，它的定义在vmlinux.lds.s中：

#if L1_DATA_A_LENGTH

# define LDS_L1_A_DATA *(.l1.data)

# define LDS_L1_A_BSS *(.l1.bss)

# define LDS_L1_A_CACHE *(.data_l1.cacheline_aligned)

#else

# define LDS_L1_A_DATA

# define LDS_L1_A_BSS

# define LDS_L1_A_CACHE

#endif

.data_l1 L1_DATA_A_START : AT(LOADADDR(.text_l1) + SIZEOF(.text_l1))

{

. = ALIGN(4);

__sdata_l1 = .;

LDS_L1_A_DATA

__edata_l1 = .;

. = ALIGN(4);

__sbss_l1 = .;

LDS_L1_A_BSS

. = ALIGN(32);

LDS_L1_A_CACHE

. = ALIGN(4);

__ebss_l1 = .;

}

很明显，它将L1_DATA_A这块内存划分为普通数据，BSS数据和CACHE。

因此相应地在LDF文件中进行修改：

L1_data_a_1

{

INPUT_SECTION_ALIGN(4)

___l1_data_cache_a = 0;

INPUT_SECTIONS($OBJECTS_CORE_A(L1_data_a) $LIBRARIES_CORE_A(L1_data_a))

INPUT_SECTIONS($OBJECTS_CORE_A(.data_l1.cacheline_aligned) $LIBRARIES_CORE_A(.data_l1.cacheline_aligned))

/*$VDSG<insert-input-sections-at-the-start-of-l1_data_a> */

/* Text inserted between these $VDSG comments will be preserved */

/*$VDSG<insert-input-sections-at-the-start-of-l1_data_a> */

RESERVE(heaps_and_stack_in_L1_data_a, heaps_and_stack_in_L1_data_a_length = 2048,4)

} > MEM_A_L1_DATA_A

L1_data_a_bsz ZERO_INIT

{

INPUT_SECTION_ALIGN(4)

INPUT_SECTIONS( $OBJECTS_CORE_A(L1_bsz) $LIBRARIES_CORE_A(L1_bsz))

} > MEM_A_L1_DATA_A

L1_data_a

{

INPUT_SECTION_ALIGN(4)

__sdata_l1 = .;

INPUT_SECTIONS($OBJECTS_CORE_A{DualCoreMem("CoreA")}(cplb_data) $LIBRARIES_CORE_A{DualCoreMem("CoreA")}(cplb_data))

INPUT_SECTIONS($OBJECTS_CORE_A(cplb_data) $LIBRARIES_CORE_A(cplb_data))

INPUT_SECTIONS($OBJECTS_CORE_A(voldata) $LIBRARIES_CORE_A(voldata))

INPUT_SECTIONS($OBJECTS_CORE_A(constdata) $LIBRARIES_CORE_A(constdata))

INPUT_SECTIONS($OBJS_LIBS_INTERNAL_CORE_A(data1))

INPUT_SECTIONS($OBJS_LIBS_NOT_EXTERNAL_CORE_A(data1))

INPUT_SECTIONS($OBJECTS_CORE_A(data1) $LIBRARIES_CORE_A(data1))

INPUT_SECTIONS($OBJECTS_CORE_A(.edt) $LIBRARIES_CORE_A(.edt))

INPUT_SECTIONS($OBJECTS_CORE_A(.cht) $LIBRARIES_CORE_A(.cht))

INPUT_SECTIONS($OBJECTS_CORE_A(.l1.data) $LIBRARIES_CORE_A(.l1.data))

/*$VDSG<insert-input-sections-at-the-end-of-l1_data_a> */

/* Text inserted between these $VDSG comments will be preserved */

/*$VDSG<insert-input-sections-at-the-end-of-l1_data_a> */

__edata_l1 = .;

} > MEM_A_L1_DATA_A

bsz_L1_data_a ZERO_INIT

{

INPUT_SECTION_ALIGN(4)

__sbss_l1 = .;

INPUT_SECTIONS($OBJECTS_CORE_A(bsz) $LIBRARIES_CORE_A(bsz))

INPUT_SECTIONS($OBJECTS_CORE_A(.l1.bss) $LIBRARIES_CORE_A(.l1.bss))

__ebss_l1 = .;

} > MEM_A_L1_DATA_A

L1_data_a_stack_heap

{

INPUT_SECTION_ALIGN(4)

RESERVE_EXPAND(heaps_and_stack_in_L1_data_a, heaps_and_stack_in_L1_data_a_length , 0, 4)

ldf_heap_space = heaps_and_stack_in_L1_data_a;

ldf_heap_end = (ldf_heap_space + (heaps_and_stack_in_L1_data_a_length - 4)) & 0xfffffffc;

ldf_heap_length = ldf_heap_end - ldf_heap_space;

} > MEM_A_L1_DATA_A

在这里仍然保留了VDSP向导对heap的定义，因为不知道要引用的VDSP库中是否要使用malloc这样的函数来分配内存。

1 参考资料

uclinux-2008R1.5-RC3(bf561)到VDSP5的移植(47)：per_cpu的奇怪问题(2009-1-22)

uclinux-2008R1.5-RC3(bf561)到VDSP5的移植(48)：__start___param(2009-1-22)

uclinux-2008R1.5-RC3(bf561)到VDSP5的移植(49)：likely(2009-1-24)

uclinux-2008R1.5-RC3(bf561)到VDSP5的移植(50)：.spinlock.text(2009-1-24)

uclinux-2008R1.5-RC3(bf561)到VDSP5的移植(51)：CONFIG_LOG_BUF_SHIFT(2009-1-24)