Re: [Geekos-devel] IDE

[David H. <da...@cs...>]

On Tue, Feb 05, 2002 at 11:25:25PM +0000, Vishal Soni wrote:
> 
> Hi,
> 
> The IDE driver is almost ready...just need to do some final phases of 
> testing.

Wow, that was fast work!

> Now i have questions regarding the interface and certain implementations.
> 
> Do we need to implement the disk scheduling "elevator algorithm" or do you 
> just want a basic read write ability to the disk. I think this would be 
> required down the line for sure. But for now i could give u the basic driver 
> to test the VM swapping.

Basic I/O is fine for now.  (Also, paging to disk is months in
the future, as I'm still trying to get basic virtual memory
to work.)

> Again a question about LBA and CHS...after looking into some implementations 
> of file systems like FFS and EXT2 i absorved that disk geometry plays an 
> important role in file system performance...
> 
> So most of the implementations talk in terms of cylinders head and sectors. 
> So do we want an LBA ability in our drive

Disclaimer: I really don't know much about hard drives or
file systems.

Having said that, it's my impression that the geometry reported
by modern drives is somewhat ficticious.  For example, there are
more physical sectors on outer tracks than inner tracks, so
the uniform CHS model isn't really strictly accurate.

I'd be interested to see any documentation, papers,
experimental results, etc. on this topic.

In general, GeekOS is at such an early stage that I'd rather
keep things as simple as possible, and wait until later to
think about performance.

So, my vote is still for LBA.

-Dave