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本帖最后由 zc_fly 于 2014-8-19 16:53 编辑 # f. a; ~8 N0 E2 D$ i O/ G
1 m: Y( s' v& w5 z) A& _7 g' x5 nOMAPL138的ARM端对共享区内存进行直接访问,代码如下所示:#include <stdio.h>
% d- A s( O* T4 @4 {- m#include <unistd.h># a" O0 d! V1 u
#include <sys/mman.h>
6 ~2 @0 r0 t8 {; e#include <sys/types.h>& [* A. L: Q8 R" T. l! j
#include <fcntl.h>
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& l2 V5 @ J, i# |* x( R#define SHAER_RAM_BASE_ADDR (0x80000000) & u% p0 W6 I3 e6 `2 `
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typedef struct
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2 c7 {" k+ Y2 m, E3 l unsigned int a;
2 E5 X7 W5 r& O5 y unsigned int b;
% V6 A& \- w* z8 j5 P unsigned int packet_cout;5 [7 s. o* E. O* F h/ H. \! [
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;. Z" c& x& o$ Z- c8 C" s6 w: u8 s
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);+ e' d2 }1 w3 c$ R
unsigned int count_copy = 0;
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int main(): N0 S' m' V0 Q/ r4 V1 I& `# F o* Q
{
x, G2 T. y/ r# C1 f& u( J pRX_MSG_PROTOCOL pshreRAM = NULL;
9 [0 F% U& ~9 Q( s. m pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;/ f9 j& I: y" T6 Z
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read_MSG_buffer(pshreRAM);" u1 o8 e, z# b, @( J
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)# B D q, ~$ ]2 R9 o
{
) @6 i4 O+ E& U RX_MSG_PROTOCOL buf;
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4 ^( _, c1 r; S, C Y% j buf.a = pshreRAM->a;
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buf.packet_cout = pshreRAM->packet_cout;
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9 C2 D! C7 [* E# T3 E* D if(buf.packet_cout != count_copy)
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$ o6 p2 y, @0 A printf("a is %d\n", buf.a);
& M9 z. n" @2 e& Y2 v& e printf("b is %d\n", buf.b);1 Q8 j' N4 U0 p1 z2 I5 b" Q( T
printf("count is %d\n", buf.packet_cout);. b1 g* H) \- F$ X
count_copy = buf.packet_cout;
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% I2 e$ U: S1 \5 V+ \ else
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printf("No effective message!");
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' V8 B, y) J7 I8 i4 z/ O2 L6 A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。
+ ]8 k/ G( l4 g+ z: R [' y7 X/ ~' Y使用下面代码,对内存使用了mmap函数后:7 C \# c5 Q' G, |/ J& X: D
#include <stdio.h>' A( Q" R1 {% S3 L7 c" e# ~' e( U. @' V
#include <unistd.h>2 E( ]; z% M5 _/ w- o4 ?5 b
#include <sys/mman.h>
0 n' b) X2 B- E/ a; T+ D. U* G; ?#include <sys/types.h>
7 B t# K7 g. W+ s0 A6 Z#include <fcntl.h>6 y0 s# ]: E/ [* m
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#define SHAER_RAM_BASE_ADDR (0x80000000)! g: v$ \' m' E) G: C3 u
#define SHAER_RAM_SIZE (0x20000) C; D( Y5 k8 J! ^+ a
1 E3 B( m$ }; W8 j1 z! [typedef struct' {' Y- i" X/ W# O; |) R u3 U
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unsigned int a;
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unsigned int packet_cout;
" J# ~' {% \7 l' y& F) K% m}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;0 k) I: j* D# P5 B" K4 u
a+ A( B" L0 wvoid read_MSG_buffer(int *baseaddr);
5 Y* U- d) m/ q9 A2 Runsigned int count_copy = 0;
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int main()
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, j! h! c0 s, M int fd;
' R4 r& {& V2 ~9 h2 E& J1 C int *mem = NULL;' y. L1 u) J( [5 i ], G* T
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if((fd = open("/dev/mem", O_RDWR)) <0) N9 t l% F/ u2 ]
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perror("open error");
% {$ N/ B! e1 l" K* |) S return -1;
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mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);: `/ N2 k! X" Y8 ]9 \# U n' r4 ]
& O- T6 K8 u! M while(1)
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read_MSG_buffer(mem);" z; j/ X+ N" |: l2 [( F" r' i5 Q9 C8 L
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! K+ |; |' R3 P# @: Z/ E( Lvoid read_MSG_buffer(int *baseaddr)
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pRX_MSG_PROTOCOL pshreRAM = NULL;! W' \; [/ j# t+ T# C. c% V6 C
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pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;, I3 ^6 |0 W1 y+ @. j1 Y
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if(pshreRAM->packet_cout != count_copy)
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8 Y" l" d- F* C" b8 W5 Q printf("a is %d\n", pshreRAM->a);- c6 l9 ^5 ?: X
printf("b is %d\n", pshreRAM->b);( s- N3 Z) k# F+ t8 F, M3 ^
printf("count is %d\n", pshreRAM->packet_cout);, O( K# P' [7 P0 R0 d0 H( T. U% f
count_copy = pshreRAM->packet_cout;2 F% E( n% m4 i
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else: I8 H7 D# k9 Q
{
3 K- ~2 c7 b1 u4 \ printf("No effective message!\n");
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" S2 `8 v+ L. J, q3 a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???0 l9 `& v. @& }8 k9 p
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