Subject: Re: ahc and Semantics of the "COMPLETE" return code
To: Matthew Jacob <>
From: John S. Dyson <>
List: tech-kern
Date: 06/24/1997 00:41:13
> No, we're cognizant of these issues- it's just that for some large
> mass storage applications, transfers of < 1MB are uninteresting.
> I should note that the Solaris/x86 AHC driver is also limited to 17
> S/G limit- which makes for incompatibilities with tapes written under
> Solaris/Sparc.
> >
> >Pluto made a few changes to physio to allow a user process to specify a
> >physical address to a chunck of device memory and the I/O we do can
> >also be quite large, but it's always to a contiguous piece of memory, so
> >the S/G list length doesn't affect us.
> >
> Ah- that's nice- it'd be nice if a {read,write}{v} would just do the
> right thing, though.
I have been planning on upgrading the FreeBSD I/O code to support whatever
the hardware is limited to -- not just the (we all admit) lousy 64K limit.

In fact, if Justin would do the I/O data structure mods, and other calling
sequence changes -- I'll to the middle (VM/VFS) layer changes :-).