Date: Thu, 3 Jun 1999 14:36:38 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Jos Backus <Jos.Backus@nl.origin-it.com> Cc: Wilko Bulte <wilko@yedi.iaf.nl>, zzhang@cs.binghamton.edu, freebsd-hackers@FreeBSD.ORG Subject: Re: The choice of MAXPHYS Message-ID: <199906032136.OAA00394@apollo.backplane.com> References: <19990603172907.A20792@hal.mpn.cp.philips.com> <199906031730.TAA00686@yedi.iaf.nl> <19990603231216.A36464@hal.mpn.cp.philips.com>
next in thread | previous in thread | raw e-mail | index | archive | help
:On Thu, Jun 03, 1999 at 07:30:20PM +0200, Wilko Bulte wrote:
:> 20 bits. But older cards can do no more than 64 kB.
:
:Indeed, 20 bits (=1 Mbyte) for the address, 16 bits for the transfer counter
:(offset).
:
:--
:Jos Backus _/ _/_/_/ "Reliability means never
MAXPHYS is ultimately a limitation on the size of the b_pages array in
the struct buf structure. The default is 128 KBytes. Device Drivers are
supposed to break up I/O's into manageable sections themselves.
Maybe when the buffer I/O / VFS subsystem is rewritten later this year
we can get rid of the artificial limitations.
-Matt
Matthew Dillon
<dillon@backplane.com>
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199906032136.OAA00394>