Kernel mode to User Mode

Kernel mode to User Mode

Post by Mikael Chambo » Tue, 10 Apr 2001 19:52:55



Hi,

Could someone explain me clearly what is the difference between the
kernel mode and user mode ??

In the book "Understanding the linux kernel p 252", I road that
the kernel checks if a signal has arrived when switching from user
mode to kernel mode.

Can someone give me the .c file where this is done ?? I would like
to add something..

Thanks for all,

Mikael Chambon

 
 
 

Kernel mode to User Mode

Post by Kasper Dupon » Tue, 10 Apr 2001 22:40:33



> Hi,

> Could someone explain me clearly what is the difference between the
> kernel mode and user mode ??

> In the book "Understanding the linux kernel p 252", I road that
> the kernel checks if a signal has arrived when switching from user
> mode to kernel mode.

It is not when switching from user mode to kernel mode,
it is when switching from kernel mode back to user mode.

Quote:

> Can someone give me the .c file where this is done ?? I would like
> to add something..

It is not done in a .c file, it is done in assembler
code.

arch/i386/kernel/entry.S

The do_signal() function is in

arch/i386/kernel/signal.c

Quote:

> Thanks for all,

> Mikael Chambon

--
Kasper Dupont

 
 
 

1. kernel mode to user mode overhead

Does anyone have real world measure mentregarding the cost of making user to
kernel
mode transition? I am evaluating the possibility of porting some of the
fucntion into an FPGA
and would like to assess the performance of speed up from the hardware
implemenation.

Are there any reference out there?

Thanks,

Jimmy

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