I/O port protection

Daniel Vandersee dvandersee at escrypt.com
Fri Jan 12 00:12:46 CET 2007

Adam Lackorzynski wrote:
> On Thu Jan 11, 2007 at 22:25:56 +0100, Daniel Vandersee wrote:
>> is it possible to allow I/O page mapping at the RMGR for a newly created
>> task (using l4_task_new) as it were possible using the "allow_cli" flag
>> in the roottask configuration?
>> Usually the pager of the newly created task would handle its I/O
>> pagefaults. Unfortunately this won't work here as this particular task
>> (L4 loader) tries to directly map I/O pages using an IPC call to the
>> ressource manager.
>> So the question is: How can I tell the ressource manager to allow I/O
>> mapping for this particular task?
> The loader can be configured to allow only specific ports for specific
> applications. roottask just gives them out, so it already does this?!

Yes, of course, but it seems that the loader is not allowed to map an
I/O page (task #d2 is the L4 loader):
> ROOT: Task #d2 is not allowed to execute cli/sti
>  D2.03:loader  | linux_drivers,#10: Can't map I/O space, ROOT denies page (result=0000
>  D2.03:loader  : 4000)

IMO this is because the loader was not started with the "allow_cli" flag
turned on. The loader was started by another server (using l4_task_new)
- not by the roottask.


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