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Possible problem with accessing DVDs larger than 4GB


I have been testing the latest beta versions of the WinUAE Amiga emulator
with several versions of NetBSD. That's shown up a few bugs in WinUAE's
SCSI and MMU emulation which have been fixed. Hopefully the next release
should be useful for testing NetBSD/amiga with emulated 68030/040/060.
(WinUAE works mostly fine under Wine.)

I came across one issue which might actually indicate a problem with
NetBSD though. I'm hoping someone has access to a real Amiga with DVD-ROM
drive in order to check whether it happens on a real machine.

Testing NetBSD 6.0.1 with emulated SCSI or ATAPI DVD drive, when you try
to access a DVD which is larger than 4GB (2^32 bytes), the accessible
range is truncated modulo 2^32.

For example, one ISO image I used is 4933021696 bytes long.
4933021696 - 2^32 = 638054400 = 311550 * 2048.

Using dd, it stops the 311550-sector point:
# dd if=/dev/cd0c of=/dev/null bs=2048 iseek=311540
9+0 records in
9+0 records out
18432 bytes transferred in 0.089 secs (207101 bytes/sec)

That issue affects both emulated SCSI and ATAPI DVD drives. (The Debian
m68k 3.1r8 installer shows a similar problem for emulated SCSI DVD drive
only; ATAPI works fine there.)

I did the same test with NetBSD 1.6.2. Both SCSI and ATAPI DVD drives seem
to work fine, no truncated accessible range. NetBSD 1.3.3 with SCSI DVD
drive also seems fine (1.3.3 didn't support ATAPI drives).

-- Mark

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