[iyonix-support] Re: Bugs in SCSIFS?

On 21 Jun 2007 Martin Wuerthner <lists@xxxxxxxxxxxxxxx> wrote:
> In message <1182411552.467a2b201df87@xxxxxxxxxxxxxxxxx>
>           davehigton@xxxxxxxxxxxxx wrote:
>> What happens when a drive with a >2GB partition is offered around?

> I am not sure whether it is offered around in the first place - there
> would not be any point in doing so because there would be no way to
> claim the partition. The only way it can be claimed is by an image
> filing system returning a filetype, which is then used to interpret
> the partition as an image file, but that only works for <2GB.

RO5 FileCore has been offering round the >2GB partitions, as people 
have experianced problems when trying to use hard drives previously 
used in PCs and formatted to FAT32. DOSFS then hangs when it attempts 
to interpret the incorrect data from reads beyond the 2GB limit.

(The cure for this is to *Unplug DOSFS, install the disc, format with 
HFORM and then *RMReinit DOSFS).

>> Does it become available for block/sector access via FileCore%SCSI?

> Nothing stops a program from using sector operations on a disc that
> appears unformatted. Not via FileCore%SCSI though, you would access
> the disc via SCSIFS.

The foreign format whole disc and disc image file operations should 
have been kept separate, but unfortunately the system was simplified 
so the same image filing system code could be both, accessing both 
types via a file handle with the associated 32bit restriction on file 
position addressing.

Whats needed is for the Identify disc call to pass round a DiscOp SWI 
to allow the image filing system to directly read/write via under 
lying filing system calls (ADFS for hard discs, SCSIFS for USB 
drives). There are 3 such calls, byte orientated DiscOp's (defunct as 
limited to 4GB), sector orientated SectorOp's (up to 2TB) and byte 
orientated DiscOp64's (up to something ridiculous), going for the 
latter in any new mechanism is sensible.

Cheers
---Dave

-- 
______________________________________________________________________

David J. Ruck   Phone: +44- (0)7974 108301   Email: druck@xxxxxxxxxxxx
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