From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Kendall Bennett <KendallB@scitechsoft.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Running user processes in kernel mode; Java and .NET support in kernel
Date: Wed, 20 Oct 2004 19:59:37 +0100 [thread overview]
Message-ID: <1098298776.12366.16.camel@localhost.localdomain> (raw)
In-Reply-To: <4173BC21.24859.11899F91@localhost>
On Llu, 2004-10-18 at 20:50, Kendall Bennett wrote:
> Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
>
> > Why would I care ? I need the MMU for paging and to avoid
> > fragmentation of the system. If I have the MMU on then memory
> > protection checks are free.
> >
> > Except in 4G/4G mode syscalls are extremely cheap too nowdays.
>
> Yes, but kernel mode support in user programs would allow user mode
> device drivers to do stuff that currently cannot be done at all from user
> space such as handling interrupts and scheduling DMA operations.
DMA doesn't need the kernel's help except for when you want to manage
security - DRI is quite special in that way. A driver to provide
mmapable DMA memory is trivial. IRQ's are *much* harder because you have
to clear the IRQ source in the IRQ handler, but people have code that
does this and then sends signals.
next prev parent reply other threads:[~2004-10-20 20:08 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-16 4:11 Running user processes in kernel mode; Java and .NET support in kernel Simon Kissane
2004-10-16 12:59 ` Simon Kissane
2004-10-17 19:53 ` Denis Vlasenko
2004-10-18 2:16 ` Jon Masters
2004-10-17 2:27 ` Alan Cox
2004-10-18 19:50 ` Kendall Bennett
2004-10-20 18:59 ` Alan Cox [this message]
2004-10-17 4:00 ` Lee Revell
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