Hi Jeremy :-)

>> Replaying a 12 May 2005 mail :-)
>>> [Freedos-kernel] Analysis: Support for sector sizes != 512 bytes

> Thank you for reviewing and providing a suggested road map.

Well, that old mail is nice for reference, but I would still say:

> So I suggest to support nonstandard sector sizes ONLY for drives which
> are connected to separate drivers (e.g. ramdisks, USB drives, ZIP...).
> To make that possible...

For my current taste, this also implies that we do not NEED any
support for sectors ABOVE 512 bytes. It makes memory footprints
of buffers etc larger and we would only support 4096 byte sector
size for non-boot disks for the moment anyway, where an EXTERNAL
(not in the kernel but loaded in config.sys) block device driver
could easily map things into a "virtual" 512 byte sector size.

Of course in general, it is nice to be flexible. And some users
of ramdisks and romdisks would be happy about support for some
SMALLER sector sizes. As for the LARGER than 512 byte sectors,
I would really like a CACHE based solution to make access more
"large block" oriented. Maybe including write pooling. SSDs and
USB flash sticks would be happy about 4 kB, 32 kB or even more
minimum write sizes, of course also with block-aligned writes.

I do NOT recommend a full delayed write cache: It is a lot of
work to make sure that writes always go to disk before you do
something stupid (reboot, crash, change disks) and you already
gain a lot of performance with a SMALL pooling buffer IMHO.

> I have a few other things in my todo queue but once done I will look
> further into this.  I would like to add support for GPT disks first,
> which I think will be much simpler and I can test...

I totally agree and as you see in my mail from a few hours ago,
GPT is not hard to implement as long as you only care about FAT.

> I have a little bit of time off in February so maybe
> I can make significant progress then.

Maybe a strange off-topic, but I have some time off this spring,
but instead of programming, I wanted to visit some FreeDOS people
in western Europe :-) If you are interested, contact me off-list.

Regards, Eric

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