Dear Mark,
When I was using MO device , following messages showed in
our /var/log/messages.
The kernel version is kernel-2.6.16.16.
kernel: Cmd len 00001000 Cmd underflow 00000400
This messages is reported from dpt_i2o driver.
It is reported when request_bufflen member/underflow member
of the Scsi_Cmnd structure is not match.
---------------------------------------
dpt_i2o.c
static s32 adpt_scsi_to_i2o(adpt_hba* pHba,
Scsi_Cmnd* cmd, struct adpt_device* d)
{
:
len = cmd->request_bufflen;
:
if(cmd->underflow && len != cmd->underflow){
printk(KERN_WARNING"Cmd len %08X Cmd underflow %08X\n",
len, cmd->underflow);
}
:
}
---------------------------------------
The request_bufflen member/underflow member is set in sd driver.
But, each sector size is not match except 512 bytes.
---------------------------------------
sd.c
static int sd_init_command(Scsi_Cmnd * SCpnt)
{
:
this_count = SCpnt->request_bufflen >> 9;
:
if (sdp->sector_size == 1024) {
if ((block & 1) || (rq->nr_sectors & 1)) {
printk(KERN_ERR "sd: Bad block number requested");
return 0;
} else {
block = block >> 1;
this_count = this_count >> 1;
}
}
if (sdp->sector_size == 2048) {
if ((block & 3) || (rq->nr_sectors & 3)) {
printk(KERN_ERR "sd: Bad block number requested");
return 0;
} else {
block = block >> 2;
this_count = this_count >> 2;
}
}
if (sdp->sector_size == 4096) {
if ((block & 7) || (rq->nr_sectors & 7)) {
printk(KERN_ERR "sd: Bad block number requested");
return 0;
} else {
block = block >> 3;
this_count = this_count >> 3;
}
}
:
SCpnt->underflow = this_count << 9;
}
---------------------------------------
There are no problem for the hard disk because of 512 bytes in the sector size.
But, when I tested MO media(1.3GB), the sector size was 2048 byte.
I have 2 questions.
1. I think the value of underflow is a calculation mistake.
Is it true?
2. What is the purpose to compare the values of
request_bufflen member/underflow member with dpt_i2o driver?
I'm not participated in the linux-scsi mailing list.
Please reply to the following addresses.
E-Mail : sakurai_hiro@xxxxxxxxxxxxxxxx
Best Regards
Hiroomi Sakurai
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