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本帖最后由 zc_fly 于 2014-8-19 16:53 编辑 " F# P2 P6 q1 Y5 B# X+ [
4 V, i- N2 @* k0 x4 k7 UOMAPL138的ARM端对共享区内存进行直接访问,代码如下所示:#include <stdio.h>& H6 M& C; t2 J8 j. S/ V4 X
#include <unistd.h>
" O8 _: ~/ l A! e/ g! I#include <sys/mman.h>) @; o" Y+ F+ U0 W# n
#include <sys/types.h> a; U+ m4 X2 m$ u1 m0 T
#include <fcntl.h>
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#define SHAER_RAM_BASE_ADDR (0x80000000) 0 t" H8 l9 T7 I# M) Q6 h
+ t: N/ Z0 W" L6 G9 {: c: F7 stypedef struct
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unsigned int a;
; S2 J& [# ~& a0 D+ L unsigned int b;; ?( p7 H1 h' s' K
unsigned int packet_cout;: i" {2 q+ q. ^" P# X5 O
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);
' K( a( O0 v1 R2 N6 H9 vunsigned int count_copy = 0;* T- [4 v/ C: I2 r8 M- c
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int main()2 }' E. h. m5 m% v2 x
{
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pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;
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while(1)
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}
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- ?! z1 Z9 g, w6 t2 Cvoid read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)
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RX_MSG_PROTOCOL buf;- n6 i6 [: R: j0 t* \$ Y9 x
6 p* d/ E7 K3 |) C7 I buf.a = pshreRAM->a;
1 l8 Q+ p0 F, h0 I: Q: t buf.b = pshreRAM->b;0 b: C0 H8 o& ~- Y
buf.packet_cout = pshreRAM->packet_cout;; }$ L% {/ o$ U+ K1 K6 i" k
2 P) X% p2 i4 [0 M' d if(buf.packet_cout != count_copy)" k! G" w6 c- ^/ P! | c; K
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printf("a is %d\n", buf.a);- J9 c( j/ ]0 E" x# U! c& g& u8 Z9 @
printf("b is %d\n", buf.b);4 d& x4 w6 |; \* @9 u
printf("count is %d\n", buf.packet_cout);0 B6 b0 |. ~% V
count_copy = buf.packet_cout;
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printf("No effective message!");$ m/ n( M2 g# ~3 h
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}
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/ H1 g1 H; q4 x' e8 I1 d但是出现segmentation fault的问题,这是什么原因啊???我在DSP端烧写了一段小程序,向共享区0x80000000位置写入数据,用CCS 测试发现写入成功。 T/ \1 G0 N! O' ~$ f( i' l
使用下面代码,对内存使用了mmap函数后:7 B0 m9 O2 v% ?
#include <stdio.h>0 l* ?9 F2 ?1 j* ^9 u' r
#include <unistd.h>0 j# W4 {, X# p- M- I) u
#include <sys/mman.h>
0 `+ S0 B! d/ k; O( s#include <sys/types.h>
& `6 w. x# s2 e2 o#include <fcntl.h>
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; L# e. A: t, H6 s8 N7 ~9 e#define SHAER_RAM_BASE_ADDR (0x80000000)! q( E/ C7 x, b" ~% A( ^
#define SHAER_RAM_SIZE (0x20000) ; q' w9 D& z9 a4 \
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typedef struct6 R5 F! q# g' L" b+ I- Q
{" {5 Q+ G x, n+ i& G- A
unsigned int a;
3 ]6 p |3 Y$ F1 k6 [, D8 z unsigned int b;
# J; a0 t8 w. }7 ^' D( f unsigned int packet_cout;3 M; H* H& |3 | v
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;
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. k$ ?/ [- p9 l) ^" B3 Hvoid read_MSG_buffer(int *baseaddr);
7 A! w9 {2 A3 e& T4 i9 r0 Sunsigned int count_copy = 0;* Q; J$ x( T; u8 c6 j0 H
3 O+ Q( X1 B5 F7 hint main(), e" R2 K) {/ }7 ]
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int fd;7 ] N% f1 r, G+ H1 i! z" {1 o
int *mem = NULL;
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: ? |4 h+ k4 y2 f& p8 m+ d if((fd = open("/dev/mem", O_RDWR)) <0)$ w" w$ K. B# ?
{
) P& f j9 U& [4 w4 ^& p0 Z( g perror("open error");
7 q+ j; ~. C, Q: w return -1;. T+ @2 w+ e6 C' m: Z
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mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
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while(1)9 s* g! ?6 A8 |. r3 L: n" u
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read_MSG_buffer(mem);2 O6 A0 n4 a& d
}
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void read_MSG_buffer(int *baseaddr)
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, |7 `: Y4 e, }% F6 C pRX_MSG_PROTOCOL pshreRAM = NULL;$ Q9 d/ P3 b# Y% v. j- u
0 T1 W8 |0 c" A7 N. D0 _$ e0 r# B pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;" }* C9 x' ^$ y5 K2 a: V
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if(pshreRAM->packet_cout != count_copy)
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printf("a is %d\n", pshreRAM->a);% T; W; @4 b* m- E4 B* E7 Z2 j$ F
printf("b is %d\n", pshreRAM->b);% B$ b6 j) i4 O+ D& O
printf("count is %d\n", pshreRAM->packet_cout);
4 y2 ~# K! Z3 Y- @/ e! k! S count_copy = pshreRAM->packet_cout;) H6 v$ w8 l5 v- D: P2 b' u4 x6 e
}
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/ a+ V/ w6 C# |5 }$ J6 D printf("No effective message!\n");
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没有出现segmentation fault这个错误,但是读出来的数据均为0。这该怎样解决啊???主要问题还是在Linux系统下,OMAPL138是否可以直接访问映射地址???该怎样实现???, v" N& @3 G" U% u0 m2 c& d
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