[9fans] seek offset

[arisawa@ar.aichi-u.ac.jp arisawa@ar.aichi-u.ac.jp]

Hello 9fans,

schwartz@bio.cse.psu.edu wrote:
>If you send the boddle to the list it will get into the archives at least.

I changed two files:
	/sys/src/9/pc/devata.c
	/sys/src/boot/pc/hard.c
for large IDE.

I worked on `devata.c' sent by Forsyth and he forbid me
to redistribute the source without his permission.

It was fairly easy to fix hard.c.
Changing the meaning `cap' is all to do.

term% diff hard.c 877058463/hard.c
222,224c222,223
< 			print("hd%d: LBA %d sect/trk , %d bytes/sect, %lud sectors\n",
< 				drive->driveno, drive->sectors, drive->bytes,
< 				drive->cap);
---
> 			print("hd%d: LBA %d sectors, %d bytes\n",
> 				drive->driveno, drive->sectors, drive->cap);
226c225
< 			print("hd%d: CHS %d/%d/%d, %d bytes/sect, %lud sectors\n",
---
> 			print("hd%d: CHS %d/%d/%d %d bytes\n",
228c227
< 				drive->sectors, drive->bytes, drive->cap);
---
> 				drive->sectors, drive->cap);
520c519
< 		dp->cap = dp->sectors;
---
> 		dp->cap = dp->bytes * dp->sectors;
539c538
< 		dp->cap = dp->cyl * dp->heads * dp->sectors;
---
> 		dp->cap = dp->bytes * dp->cyl * dp->heads * dp->sectors;
661c660
< 	pp->end = dp->cap;
---
> 	pp->end = dp->cap / dp->bytes;


schwartz@bio.cse.psu.edu also wrote:
>What's the situation with >2gb scsi disks?

As far as `b.com' is concerned, 877058463/scsi.c have been
already fixed as shown bellow:
term% grep cap scsi.c
scsi.c:	case ScsiGetcap:
scsi.c:scsicap(int dev, void *p)
scsi.c:	cmd = scsicmd(dev, ScsiGetcap, scsibuf(), 8);
scsi.c:	pp->end = dp->cap;
scsi.c:		if(scsibread(dev, b, 1, dp->bytes, dp->cap-1) <= 0){
scsi.c:		if(scsicap(i, buf))
scsi.c:		sdrive[i].cap = ((buf[0]<<24)|(buf[1]<<16)|(buf[2]<<8)|buf[3])+1;
scsi.c:		print("scsi%d: cap %lud, sec %d\n", i, sdrive[i].cap, sdrive[i].bytes);



It is uncertain for me whether kernel support large scsi for kfs or not.
We can find the last update of `devwren.c' in 824494162.rc.
Taking a quick look at the code, it seems there is no problem.

I have not experienced large scsi except for file server.
It is best to get exact answer from the people in bell-labs.


Thanks,

Kenji Arisawa
E-mail: arisawa@aichi-u.ac.jp