Date: Fri, 23 Feb 2001 13:15:18 +0800 From: Rex Luo <rexluo@synology.com> To: freebsd-scsi@FreeBSD.ORG Subject: residual count not zero in target mode Message-ID: <200102230515.NAA00874@synology.com>
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Dear all,
I have a programming problem, hope someone knows that.
I have two scsi channel, one(0) is configured to as initiator mode, and
another(1) is target mode. I modified FreeBSD kernel(4.1) to let target drive
behave as a direct-accessed disk.(targctor() T_PROCESSOR --> T_DIRECT).
Furthermore, I add READ_6, WRITE_6 opcode in targdone()(original is SEND,
RECEIVE), and it runs smoothly. I also modified /usr/src/share/examples/scsi_targ/scsi_target.c to add new ioctl commands to attach another real drive, and get i/o request offset, and length.(If you want to know more detail, I can show what I modified.)
Then, I use "scsi_targ -o /dev/ad0s2b -p 1 -t 8 -l 0" to enable channel 1 as
target mode.(I modified "-o" option to let input, output files are the same)
I can use "camcontrol rescan 0" to rescan bus 0, then I get a scsi da drive. I try to use sysinstall to open and issue i/o request to the drive, however, I
found that the issued i/o request's residual is not zero. It's code stack is
ahc_intr() --->
ahc_run_qoutfifo() --->
if (scb->hscb->residual_SG_count != 0)
ahc_calc_residual(scb) --->
resid = hscb->residual_data_count[2] << 16 ....
....
and it's value is not zero. If scb->ccb->csio.resid = resid is not zero, the i/o
request will be failed (it's set in dadone()), then open drive fail.
Does anyone know who will set residual_data_count[0-2]? and how to set that?
In my opinion, I think sequencer should update these values automatically,
and targetmode driver should inform initiator sequencer to update these values.
Actually, I have no idea about that, if you have some information or document
about that, or you know where I am wrong. Please let me know, thanks,
Sincerely,
Rex Luo
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