On Wed, 10 Jun 1998 11:44:01 -0600, Justin Gibbs writes:

[Jason Thorpe writes:]

>>On Wed, 10 Jun 1998 02:32:58 -0400 
>> Brian Cully <shmit@kublai.com> wrote:
>>
>>...this is just a little editorial comment...
>>
>> > It also uses FreeBSD's busdma stuff, which isn't too entirely different
>> > from NetBSD's so it shouldn't be too hard to port. I'd even be willing
>>
>>The fact that it's different _at all_ is, quite frankly, totally ridiculous.

>No.  It points to deficiencies in the NetBSD interface;
[snip]

>  I had hoped to share an identical bus dma interface with
>NetBSD, but I am unwilling to do this so long as the NetBSD interface
>sacrifices speed and memory resources for absolutely no gain in
>portability.

A lot of people looked very hard at Jason's bus-space and bus-dma
ideas, during more than a year of discussion. There was a _lot_ of
thought about portability to a very wide range of CPUs and buses.
Jason's ideas evolved to accomodate the wide range of hardware NetBSD
developers support. With people pulling for performance at the same
time.

Could you describe which parts of the original bus_dma interface which
are burning resources and speed for no good reason?  Maybe you're
right and there are gains to be made here for everyone. Maybe there
are some issues for arcane I/O buses which you haven't fully
considered.  Or maybe NetBSD is aimed more to portability in the
portability/performance tradeoff than FreeBSD
(translation: you're both right).

Without knowing just what parts of the design you object to, and why,
it's impossible to say one way or another.

I dunno about anyone else, but I'd like to hear just what you think is
wrong with NetBSD's bus-dma (sans personalities). THen we can all make
up our own minds.  (I think tech-kern is a much better venue for that
than port-i386; could you Cc: any response there, please? thanx)

--Jonathan