From mboxrd@z Thu Jan  1 00:00:00 1970
MIME-Version: 1.0
References: <3C62CE67D1FF8260C5450B3D0AE7AA1A@felloff.net>
	<CAEoi9W62qFgB2tj=aKEZ=PusHObnTwTDbGBqFBmzgmu=Sfepjg@mail.gmail.com>
	<20181011023054.2E6AC156E40C@mail.bitblocks.com>
In-Reply-To: <20181011023054.2E6AC156E40C@mail.bitblocks.com>
From: Steven Stallion <sstallion@gmail.com>
Date: Wed, 10 Oct 2018 22:20:05 -0500
Message-ID: <CAGGHmKEsHLE5-UiHnyKFR--qXOCJs-pPmABaVj1hTMdiuV3t_A@mail.gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Content-Type: text/plain; charset="UTF-8"
Subject: Re: [9fans] zero copy & 9p (was Re: PDP11 (Was: Re: what heavy
	negativity!)
Topicbox-Message-UUID: ebdd403c-ead9-11e9-9d60-3106f5b1d025

On Wed, Oct 10, 2018 at 9:32 PM Bakul Shah <bakul@bitblocks.com> wrote:
> Steve wrote "1:1 mapping of the virtual kernel address space such
> that something like zero-copy could be possible"
>
> Not sure what he meant. For zero copy you need to *directly*
> write to the memory allocated to a process. 1:1 mapping is
> really not needed.

Ugh. I could have worded that better. That was a (very) clumsy attempt
at stating that the kernel would have to support remapping the user
buffer to virtual kernel space. Fortunately Plan 9 doesn't page out
kernel memory, so pinning wouldn't be required.

Cheers,
Steve