Re: ipc security

[Johan Rydberg]

Ludovic Courtès <address@hidden> writes:

>> Still, we need in every task a contingent of pages that must not be
>> unmapped by physmem, in particular the memory the pager uses to run
>> on!  This contingent is naturally restricted in some ways (may not be
>> useful for DMA, may be fragmented, and is limited to a small amount).
>> But I don't see a problem in going for this solution if you know the
>> maximum size of the data in advance.
>
> Does this mean that the number of tasks that could possibly run in the
> system is bound by the amount of physical memory available over the
> amount of physical "unmappable" memory granted to each task?

Yes.  But the amount of memory used by the self-pager is not the thing
that puts a limit to the number of tasks that can be active at the
same time in the system.  The kernel needs physical memory for page
tables for each task, for example.  This is true for other systems
as well.

~j