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SubjectRe: Running user processes in kernel mode; Java and .NET support in kernel
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.

Just think about how nice it would be if the kernel level DRI driver
modules that are currently completely separate from the user space X
drivers could be all in one place? Then users would no longer have to
worry about making sure they upgrade their kernel so it has the correct
kernel module installed at the same time that they upgrade X or get new
drivers for their X server.

IMHO I am not sure how much speedup you would gain from kernel mode Linux
for user space programs (it might surprise us, or maybe it isn't much),
but the ability to support user mode device drivers would be good IMHO,
especially for graphics.

Regards,

---
Kendall Bennett
Chief Executive Officer
SciTech Software, Inc.
Phone: (530) 894 8400
http://www.scitechsoft.com
~ SciTech SNAP - The future of device driver technology! ~


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