Scsi - Index of

就必须设置US_FL_IGNORE_RESIDUE 这个flag 了.当时那个patch 是这样的:
===== drivers/usb/storage/transport.c 1.151 vs edited =====
--- 1.151/drivers/usb/storage/transport.c 2004-10-20 12:38:15 -04:00
+++ edited/drivers/usb/storage/transport.c 2004-10-28 10:50:42 -04:00
@@ -1058,8 +1058,7 @@
/* try to compute the actual residue, based on how much data
* was really transferred and what the device tells us */
if (residue) {
- if (!(us->flags & US_FL_IGNORE_RESIDUE) ||
- srb->sc_data_direction == DMA_TO_DEVICE) {
+ if (!(us->flags & US_FL_IGNORE_RESIDUE)) {
residue = min(residue, transfer_length);
srb->resid = max(srb->resid, (int) residue);
}
同时我们也把当时去开源社区抱怨的那位哥们的调试信息贴出来:
usb-storage: Command WRITE_10 (10 bytes)
usb-storage: 2a 00 00 00 01 37 00 00 08 00
usb-storage: Bulk Command S 0x43425355 T 0x82 L 4096 F 0 Trg 0 LUN 0 CL 10
usb-storage: usb_stor_bulk_transfer_buf: xfer 31 bytes
usb-storage: Status code 0; transferred 31/31
usb-storage: -- transfer complete
usb-storage: Bulk command transfer result=0
usb-storage: usb_stor_bulk_transfer_sglist: xfer 4096 bytes, 2 entries
usb-storage: Status code 0; transferred 4096/4096
usb-storage: -- transfer complete
usb-storage: Bulk data transfer result 0x0
usb-storage: Attempting to get CSW...
usb-storage: usb_stor_bulk_transfer_buf: xfer 13 bytes
usb-storage: Status code 0; transferred 13/13
usb-storage: -- transfer complete
usb-storage: Bulk status result = 0
usb-storage: Bulk Status S 0x53425355 T 0x82 R 3072 Stat 0x0
170
usb-storage: -- unexpectedly short transfer
usb-storage: scsi cmd done, result=0x10070000
SCSI error : return code = 0x10070000
end_request: I/O error, dev sda, sector 311
应该说这段信息清晰的打印出来整个Bulk 传输是怎么进行的.一共三个阶段,Command/Data/Status,
这里执行的命令就是WRITE_10,本来这是一次成功的传输,但是最后返回值result 却不为0,而是
0x10070000,关于这个0x10070000 如何出来的,我们稍候会知道.最后两行是scsi core 那边的代码打
印出来的,我们不用管,只是需要知道我们最终返回给scsi 核心层的一个有用信息就是srb->result.所以我
们看到scsi 那边打印了一个reture code,和我们这里的result 是一样的.其实打印的都是srb->result.
很显然,srb 这个东西相当于usb-storage 和scsi 那边的桥梁,连接了两个模块.
Ok,继续往下走.1068 行开始基于CSW 返回的状态,来判断结果了.判断的值就是bcs->Status.如果是