Re: patent on O_ATOMICLOOKUP [Re: [PATCH] loopable tmpfs (2.4.17)]

Karim Yaghmour
2002-05-25T18:24:14Z

Linus Torvalds wrote:
> - I think the microkernel approach is fundamentally broken. Karim claims
> there is no priority inversion, but he must have his blinders on. Every
> single spinlock in the kernel assumes that the kernel isn't preempted,
> which means that user apps that can preempt the kernel cannot use them.

Blinders ehh... Well, if you would care to ask I would answer.

In reality, what you point out is actually a non-issue since the hard-rt
user-land tasks are not allowed to call on normal Linux services. They
can only call on RTAI services which are exported by an extra soft-int.
These services are hard-rt, so there's no problem there.

Please, download the thing and play with it. Or, at the very least, ask
about how it works and we'll be glad to explain.

Karim

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Karim Yaghmour
karim@opersys.com
Embedded and Real-Time Linux Expert
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