[seL4] How are capabilities assigned

Sebastian Lau sebastianlau25 at gmail.com
Mon Feb 16 18:37:53 EST 2015


Cheers Gerwin and I've read some of the other 'posts' and I'm wondering,
can a process only save or hold one capability and if so is there any way
to build or have a workaround?

On Mon, 16 Feb 2015 20:24 Gerwin Klein <Gerwin.Klein at nicta.com.au> wrote:

>  Hi Sebastian,
>
>  when the kernel initialises, it creates a number of standard predefined
> capabilities and hands them to the initial thread (root task), including
> capabilities to the device regions in the machine, and Untyped capabilities
> to free memory. The initial task can then use these to set up the rest of
> the system (creating threads, page tables, IPC endpoints, loading
> executables, etc).
>
>  There is a separate tool (capDL-loader) that takes a static description
> of the capability distribution the initial thread should achieve and
> produces an initial thread for you that sets up the system accordingly.
> There is no requirement to use this tool, but it has been quite handy for
> us so far.
>
>  IPC is managed by kernel calls (Wait, Send, Call, Reply) that have an
> endpoint capability as argument.
>
>  Cheers,
> Gerwin
>
>  On 16.02.2015, at 17:54, Sebastian Lau <sebastianlau25 at gmail.com> wrote:
>
>  I have a question, how are capabilities assigned or given to processes?
> Is it through the kernel or can the root process (like init etc.) assign
> capabilities as well? Also is IPC managed by calls to the kernel? I have in
> mind to base something off of seL4 in the future but I'm not quite ready to
> start though and just want to get an understanding of how things work.
>
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