Re: [uml-devel] Question about trap handling in UML kernel

[Jeff Dike <jdike@addtoit.com>]

On Wed, Apr 11, 2007 at 07:10:36PM -0700, Haifeng He wrote:

> I have a question about trap handling in UML kernel, particularly in the
> skas0 mode.
> My understanding is that, UML will fork a kernel thread for each user
> process

UML will fork a host process for each UML address space.

> and
> this thread will go to a loop (in userspace()) and wait for signal from user
> process using
> ptrace. If a signal occurs, it will call the signal handler to handle the
> interrupt.
> Is it correct?

Yes.

> My second question is, how many kernel threads are there in skas0 mode or I
> should
> ask how many different kinds of kernel threads will be created? Is there any
> kernel thread
> in UML other than those created for user process?

There are these kinds, assuming you mean host threads -
	kernel process, runs kernel code - one per virtual CPU
	user process, runs userspace code, one per address space
	utility threads, things that are useful to have in separate
threads, like the I/O thread and SIGIO thread.

> My last question is, given a kernel thread, if it is possible that the
> execution of a thread will
> be interrupted by others other than by scheduler?

If I understand the question, no.

				Jeff

-- 
Work email - jdike at linux dot intel dot com

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