[eros-arch] Problem with the semantics of address translation and
clandau at macslab.com
Sat Sep 3 00:50:05 EDT 2005
Now that the EROS people have been alerted, I suggest keeping this
thread on CapROS-devel, and dropping eros-arch, since EROS is
officially dead. The eros-arch people can subscribe to CapROS-devel
at http://lists.sourceforge.net/mailman/listinfo/capros-devel if they
At 12:13 AM -0400 9/3/05, Eric Northup wrote:
>On Fri, 2005-09-02 at 18:05, Norman Hardy wrote:
>> On Sep 2, 2005, at 1:38 PM, Eric Northup wrote:
>> Keykos had another fix to this problem, with some advantages and
>> I quote from <http://www.agorics.com/Library/KeyKos/Gnosis/28.html>.
>That is a very useful document!
>Out of curiosity, what does "ssc" stand for?
Slot Size Code
>Am I correct interpreting
>it to be morally equivalent to EROS' biased-log segment size?
Yes. The SSC is the log, base 16, of the size of address space
defined by each "slot" (element of the array of 16 keys) in a segment
node. So if a node has SSC=5, its 16 keys define 16^5 * 16 = 2^24
>Also, error code 4 is "path passes thru node that belongs to the
>domain". Does that mean what I think it does?
It means that one of the nodes in the path is also one of the three
nodes comprising the domain.
>(Because what I think it
>means [is] that each and every time I find a tricky situation that looks like
>it might have been a bug in KeyKOS, it eventually turns out to have been
>anticipated and avoided by the KeyKOS team.)
Yes, we were very careful. It helps that we weren't operating under
any sort of deadline.
> > Perhaps the architecture should merely say for some fixed n that
>> "there is a limit of at least n levels on each portion".
>So, a valid translation path would translate at least one
>never-before-translated bit each n steps?
What I suggested in a separate message was that a valid translation
path would translate at least *four* never-before-translated bits
each n steps. That's equivalent, since bits are always translated
four at a time, but it makes it clear that the bound on translating
20 bits is 5*n.
More information about the eros-arch