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Altera_Forum's avatar
Altera_Forum
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15 years ago

The problem with custom board. (Exception access user space)

Hello everyone, I have trying to run Linux on my custom board. But, Exception occurs when you access the user space. start_kernel () is passed. kernel_init () will call the initializat...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

As (AFAIK) Futex is not yet correctly implemented with the MMU based distribution, anything can happen if you use it.

Background: NIOS does not have any atomic instructions in hardware, so in an MMU-system that does not allow to disable interrupt in userspace, the OS needs to help the userspace with these instructions, that are absolutely necessary for implementing Futex. This is (planned to be) done using the "atomic region" trick.

Maybe Hippo can jump in with a statement when this might be available.

-Michael