[iyonix-support] Re: Bugs in SCSIFS?
- From: Dave Higton <davehigton@xxxxxxxxxxxxx>
- To: iyonix-support@xxxxxxxxxxxxx
- Date: Sun, 24 Jun 2007 21:55:56 +0100
In message <467A34C6.10808@xxxxxxxxxx>
John Ballance <jwb@xxxxxxxxxx> wrote:
> hi
>
> davehigton@xxxxxxxxxxxxx wrote:
> >
> > What happens when a drive with a >2GB partition is offered around?
> > Does it become available for block/sector access via FileCore%SCSI?
> >
>
> if memory serves: it is treated as if it is a single file .. hence the
> (current) 2gb filecore file size restriction 'gets in the way' I don't
> remember any attempt to trap this situation..
It looks like we have the best of both worlds, for a change...
I just bought a 4GB USB stick to play around with. Interestingly,
I can plug it in, and a drive icon appears on the icon bar. So
long as I don't click on it, everything is OK... and my app can
read sectors from it.
I've gone back to a FAT16-formatted 1GB device to get the app up
and doing basic things. I can traverse the directory structure,
and I can save files from it. I now have to make any remaining
tweaks to get FAT32 operation working.
> various strategies have been considered, varying from allowing dosfs to
> have direct disc access in cases where it is happy it is 'talking' to a
> disc, not a file on disc, to a system that 'slices' the dos disc image
> into a sequence of 'small enough' files, much as cdvdburn does for dvd
> iso images.
Perhaps we (i.e. all parties who have something useful to
contribute) should start discussing what a revised system would do.
Let me kick off with a couple of ideas.
Firstly, we must assume that a drive is partitioned, and that it
has more than one partition. Any system must cope with that.
But how? Important information is contained in the partition
table, so it makes sense to me to pass the drive around along
with a partition number that's on offer. Reading the partition
table(s) is common code, though, so it makes sense for that to
be in the basic OS rather than duplicated in each non-FileCore
FS. So a partitioned device with more than one partition should
be offered around once per partition.
Other than that: well, all an FS needs to know is a SWI or set
of SWIs to read and write sectors on the device.
Presumably it would be possible to plug in a drive formatted to
ext2, ext3, reiserfs, or whatever, and RISC OS should be able
to read and write it. Whether that's of any use to anybody is
another matter.
One other thing: I think it's time we appropriated a partition
type code for RISC OS.
Dave
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