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Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!yeshua.marcam.com!news.kei.com!hookup!swrinde!cs.utexas.edu!howland.reston.ans.net!noc.near.net!news.delphi.com!usenet From: John Dyson <dysonj@delphi.com> Newsgroups: comp.os.386bsd.development Subject: Announcing Bounce Buffer support in FreeBSD -current Date: Fri, 25 Mar 94 00:53:54 -0500 Organization: Delphi (info@delphi.com email, 800-695-4005 voice) Lines: 25 Message-ID: <JuzOBwS.dysonj@delphi.com> NNTP-Posting-Host: delphi.com Gang, As a result of *significant* demand on the part of our user base we have added bounce buffer support for FreeBSD. This means that people with ISA machines or ISA SCSI adaptors will be able to use FreeBSD with greater than 16MB with an almost unmeasurable impact on performance. The implementation of the bounce buffers is minimally intrusive in driver design and is very efficient. Some minor additional VM support has been added to minimize the impact on non-bounced transfers. Only pages that need to be bounced are bounced (which is obviously what should be done,) and low level portions of drivers do not need to be touched. Only a minor change is necessary to the device strategy routine. Currently, only scatter/gather devices are supported, but the architecture supports other types of DMA (just not implemented yet.) If you have any problems, email me at "dyson@implode.root.com", but the preliminary user tests show that operation is transparent. John dyson@implode.root.com