Date: Thu, 22 Mar 2001 06:59:47 +0100 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: mjacob@feral.com Cc: arch@FreeBSD.ORG Subject: Re: remind me again, why is MAXPHYS only 128k ? Message-ID: <94552.985240787@critter> In-Reply-To: Your message of "Wed, 21 Mar 2001 21:53:37 PST." <Pine.LNX.4.21.0103212150360.13436-100000@zeppo.feral.com>
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In message <Pine.LNX.4.21.0103212150360.13436-100000@zeppo.feral.com>, Matthew Jacob writes: >On Thu, 22 Mar 2001, Poul-Henning Kamp wrote: > >> In message <200103212224.f2LMOrh02530@mass.dis.org>, Mike Smith writes: >> >> Another possibility for physio would be to MALLOC the pages >> >> array at the very top level of the syscall and pass it down >> >> through for use by lower layers. At the very top level, >> >> before anything is locked, the MALLOC can block safely. >> > >> >This would deal with the async physio case too. >> > >> >I'm wondering how all this will interact with the general desire to avoid >> >mapping an I/O request into linear KVM before handing it to a driver; I >> >suspect probably not a lot... >> >> That is more dependent on fixing the device driver API than anything >> else. > >Device driver API? The device driver API should be busdma, shouldn't it? We are talking about the devsw->strategy() API here. We need a way to stay moderately backwards compatible. The main change is to move b_pages into struct bio and find out how to identify drivers which need a mapping and give it to them in spec_strategy(); -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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