Subject: Re: non-512-byte-sector devices vs. UBC
To: None <>
From: Christoph Badura <>
List: tech-kern
Date: 06/14/1999 21:17:30 (Erik E. Fair) writes:

>At 14:40 -0700 6/13/99, Christoph Badura wrote:
>> (Chuck Silvers) writes:
>>>on a related note, it does seem odd that the current buf interface has
>>>the offset of the i/o (b_blkno) in sectors, but the size of the i/o
>>>(b_bcount) in bytes.  it would be more consistent for both offset and size
>>>to have the same units.  or are there devices that can read partial
>>>sectors, but only at the beginning of a sector?
>>Tape drives do that.

>But no one uses tape drives through the block device; everyone uses the
>character ("raw") device, which does not go through the buffer cache.

That our tape drivers don't go through the buffer cache does not imply
that the tape drivers don't use buffers.  In fact, they do.

Christoph Badura

	Anything that can be done in O(N) can be done in O(N^2).
	-- Ralf Schuettau (after looking at a particular piece of code)