Re: [hatari-devel] Missing DMA sector count register emulation for ACSI transfers?

[Eero Tamminen <oak@xxxxxxxxxxxxxx>]

Hi,

What about the SCSI support (ncr5380.c), does that
have the same issue?


	- Eero

If it has, fixing that probably does not help
with m68k Linux SCSI issues as there seem to
be missing SCSI commands[1], but even slight
emulation improvements are always nice...

[1]
DEBUG: raw_scsi: selected id 0
DEBUG: raw_scsi_put_data got message c0 (1/1)
DEBUG: raw_scsi_put_data got message c0 (1 bytes)
DEBUG: raw_scsi: got command byte 1a (1/6)
DEBUG: raw_scsi: got command byte 00 (2/6)
DEBUG: raw_scsi: got command byte 3f (3/6)
DEBUG: raw_scsi: got command byte 00 (4/6)
DEBUG: raw_scsi: got command byte 04 (5/6)
DEBUG: raw_scsi: got command byte 00 (6/6)
TODO : HDC: Unsupported MODE SENSE command
DEBUG: raw_scsi: no data, status = 2
DEBUG: raw_scsi: status byte read 02. Next=1
DEBUG: raw_scsi: message byte read 00. Next=1
DEBUG: raw_scsi: arbitration initiator id 7 (80)
DEBUG: raw_scsi: arbitration
DEBUG: raw_scsi: selected id 0
DEBUG: raw_scsi_put_data got message 80 (1/1)
DEBUG: raw_scsi_put_data got message 80 (1 bytes)
DEBUG: raw_scsi: got command byte 03 (1/6)
DEBUG: raw_scsi: got command byte 00 (2/6)
DEBUG: raw_scsi: got command byte 00 (3/6)
DEBUG: raw_scsi: got command byte 00 (4/6)
DEBUG: raw_scsi: got command byte 60 (5/6)
DEBUG: raw_scsi: got command byte 00 (6/6)
WARN : HDC: *** Strange REQUEST SENSE ***!
DEBUG: raw_scsi: data in 22 bytes waiting
DEBUG: raw_scsi: data in finished, 22 bytes: status phase
DEBUG: DMA initiator recv PC=001839da
DEBUG: SCSI BUS reset
sd 0:0:0:0: Device offlined - not ready after error recovery
sd 0:0:0:0: rejecting I/O to offline device
sd 0:0:0:0: [sda] Write Protect is off
sd 0:0:0:0: [sda] Mode Sense: 00 00 1f ff
sd 0:0:0:0: rejecting I/O to offline device
sd 0:0:0:0: [sda] Asking for cache data failed
sd 0:0:0:0: [sda] Assuming drive cache: write through
sd 0:0:0:0: rejecting I/O to offline device
sd 0:0:0:0: rejecting I/O to offline device
sd 0:0:0:0: [sda] Attached SCSI disk
VFS: Cannot open root device "sda" or unknown-block(8,0): error -6


On 1.9.2021 16.45, Christian Zietz wrote:
> Hello,
>
> I'm testing a (fairly exotic) harddisk driver that was bundled with DDD
> harddisks:
>
> Harddisktreiber V4.13
>    (C) 1991 by K.R.
> Digital Data Deicke
>
> (Digital Data Deicke used to be a popular Atari distributor in Germany.)
>
> ... and I found it not to be working on Hatari. First, I thought that it
> was perhaps relying on some non-standard behavior/commands of DDD
> harddisks. But meanwhile I've come to the conclusion that there is a
> detail missing in Hatari's emulation of ACSI disks.
>
> After completion of a command, the driver reads the DMA status register
> at address $FF8606. (Not to be confused with the status byte that is
> read over the ACSI bus from the actual drive.) It masks the lower three
> bits and checks for 1 (= 3'b001). But Hatari always returns a 3 (=
> 3'b011), here. Bit 0 means "no DMA error", bit 1 means "sector count
> register is not zero". The equivalent lines of code are here:
> https://git.tuxfamily.org/hatari/hatari.git/tree/src/fdc.c#n4393
>
> However, it seems that the ACSI code in hdc.c never sets the DMA sector
> count register to 0, which makes this particular disk driver fail. I've
> tested (by means of a quick hack) that zeroing the sector count register
> from Acsi_DmaTransfer() makes Hatari return the expected DMA status of
> 1, and makes the driver work.
>
> Regards
> Christian