我尝试向SSD发出scsi read(10)和write(10)。我使用this example code作为引用/基本代码。
这是我的scsi阅读:
#define READ_REPLY_LEN 32
#define READ_CMDLEN 10
void scsi_read()
{
unsigned char Readbuffer[ SCSI_OFF + READ_REPLY_LEN ];
unsigned char cmdblk [ READ_CMDLEN ] =
{ 0x28, /* command */
0, /* lun/reserved */
0, /* lba */
0, /* lba */
0, /* lba */
0, /* lba */
0, /* reserved */
0, /* transfer length */
READ_REPLY_LEN, /* transfer length */
0 };/* reserved/flag/link */
memset(Readbuffer,0,sizeof(Readbuffer));
memcpy( cmd + SCSI_OFF, cmdblk, sizeof(cmdblk) );
/*
* +------------------+
* | struct sg_header | <- cmd
* +------------------+
* | copy of cmdblk | <- cmd + SCSI_OFF
* +------------------+
*/
if (handle_scsi_cmd(sizeof(cmdblk), 0, cmd,
sizeof(Readbuffer) - SCSI_OFF, Readbuffer )) {
fprintf( stderr, "read failed\n" );
exit(2);
}
hex_dump(Readbuffer,sizeof(Readbuffer));
}
这是我的scsi写道:
void scsi_write ( void )
{
unsigned char Writebuffer[SCSI_OFF];
unsigned char cmdblk [] =
{ 0x2A, /* 0: command */
0, /* 1: lun/reserved */
0, /* 2: LBA */
0, /* 3: LBA */
0, /* 4: LBA */
0, /* 5: LBA */
0, /* 6: reserved */
0, /* 7: transfer length */
0, /* 8: transfer length */
0 };/* 9: control */
memset(Writebuffer,0,sizeof(Writebuffer));
memcpy( cmd + SCSI_OFF, cmdblk, sizeof(cmdblk) );
cmd[SCSI_OFF+sizeof(cmdblk)+0] = 'A';
cmd[SCSI_OFF+sizeof(cmdblk)+1] = 'b';
cmd[SCSI_OFF+sizeof(cmdblk)+2] = 'c';
cmd[SCSI_OFF+sizeof(cmdblk)+3] = 'd';
cmd[SCSI_OFF+sizeof(cmdblk)+4] = 'e';
cmd[SCSI_OFF+sizeof(cmdblk)+5] = 'f';
cmd[SCSI_OFF+sizeof(cmdblk)+6] = 'g';
cmd[SCSI_OFF+sizeof(cmdblk)+7] = 0;
/*
* +------------------+
* | struct sg_header | <- cmd
* +------------------+
* | copy of cmdblk | <- cmd + SCSI_OFF
* +------------------+
* | data to write |
* +------------------+
*/
if (handle_scsi_cmd(sizeof(cmdblk), 8, cmd,
sizeof(Writebuffer) - SCSI_OFF, Writebuffer )) {
fprintf( stderr, "write failed\n" );
exit(2);
}
}
在以下示例中，我做了
然后打印已写入(scsi写)和读取(scsi读)数据的十六进制转储
Read(10)
[0000] 00 00 00 44 00 00 00 44 00 00 00 00 00 00 00 00 ...D...D ........
[0010] 00 2C 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ........ ........
[0020] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ........ ........
[0030] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ........ ........
[0040] 00 00 00 00 ....
Write(10):
[0000] 00 00 00 00 00 00 00 24 00 00 00 00 00 00 00 00 ........ ........
[0010] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ........ ........
[0020] 00 00 00 00 2A 00 00 00 00 00 00 00 00 00 41 62 ........ ......Ab
[0030] 63 64 65 66 67 00 cdefg.
Read(10):
[0000] 00 00 00 44 00 00 00 44 00 00 00 00 00 00 00 00 ...D...D ........
[0010] 04 00 20 00 70 00 02 00 00 00 00 0A 00 00 00 00 ....p... ........
[0020] 04 00 00 00 41 62 63 64 65 66 67 00 00 00 00 00 ....Abcd efg.....
[0030] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ........ ........
[0040] 00 00 00 00 ....
在再次运行这三个命令之后，我应该在第一次阅读时阅读
Abcdefg。正确的？但是再次运行它们不会改变任何事情。您现在可以假设，我使用的内存仍然具有以前功能的数据，但是即使在memset(Readbuff,0,sizeof(Readbuff))发生之前运行sys_read()，我也会得到相同的结果。我以为，我尝试写入的LBA可能被禁止写入，而我读取了缓存。但是从0x00-0xFF遍历LBA地址不会发生任何变化-这意味着，我读取了相同的数据(
Abcdefg)。您是否知道使用scsi通用接口(interface)进行scsi读写的示例实现？
最佳答案
在SCSI中，LBA的单位和传输长度以块为单位，有时也称为扇区。这几乎总是512个字节。因此，您不能只读取或写入32个字节。至少，您必须执行512字节==一个块。这一点是您需要修复的大部分内容。
在scsi_write实现中，传输长度为零，因此实际上不会写入任何数据。
您应该为CDB和写入/读取数据使用不同的缓冲区。我怀疑关于这些缓冲区的困惑会导致您的实现在静态分配的数组之一的末尾和ReadBuffer上进行写操作。在valgrind下运行它，然后查看显示的内容。
最后，handle_scsi_cmd中的任何内容都可能出错。设置数据传输可能很棘手……特别是，请确保直接在I/O header 的dxfer_direction中确定数据的传输方式:SG_DXFER_TO_DEV用于写入，SG_DXFER_FROM_DEV用于读取。
查看此示例，了解如何执行read(16)。这更符合您要完成的工作。
https://github.com/hreinecke/sg3_utils/blob/master/examples/sg_simple16.c
关于linux - 使用SCSI通用接口(interface)的SCSI读取(10)和写入(10)，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/11867612/