From: "H. Peter Anvin" <hpa@zytor.com>
To: linux-kernel@vger.kernel.org
Subject: Re: How to transfer memory from PCI memory directly to user space safely and portable?
Date: 27 Nov 2000 10:36:34 -0800 [thread overview]
Message-ID: <8vu9ji$r2a$1@cesium.transmeta.com> (raw)
In-Reply-To: <00112614213105.05228@paganini> <20001126151120.V2272@parcelfarce.linux.theplanet.co.uk>
Followup to: <20001126151120.V2272@parcelfarce.linux.theplanet.co.uk>
By author: Philipp Rumpf <prumpf@parcelfarce.linux.theplanet.co.uk>
In newsgroup: linux.dev.kernel
>
> I hope count isn't provided by userspace here ?
>
> > 1. What happens if the user space memory is swapped to disk? Will
> > verify_area() make sure that the memory is in physical RAM when it returns,
> > or will it return -EFAULT, or will something even worse happen?
>
> On i386, you'll sleep implicitly waiting for the page fault to be handled; in
> the generic case, anything could happen.
>
That doesn't sound right. I would expect it to wait for the page to
be brought in on any and all architectures, otherwise it seems rather
impossible to write portable Linux kernel code.
-hpa
--
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"Unix gives you enough rope to shoot yourself in the foot."
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next prev parent reply other threads:[~2000-11-27 19:07 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-11-26 13:21 How to transfer memory from PCI memory directly to user space safely and portable? Anders Torger
2000-11-26 15:11 ` Philipp Rumpf
2000-11-26 15:36 ` Anders Torger
2000-11-27 18:36 ` H. Peter Anvin [this message]
2000-11-27 19:29 ` Philipp Rumpf
2000-11-27 19:30 ` H. Peter Anvin
2000-11-27 13:51 ` Richard B. Johnson
-- strict thread matches above, loose matches on Subject: below --
2000-11-27 13:27 aprasad
2000-11-26 13:54 ` Anders Torger
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