[coyotos-dev] Problem with Coyotos Spec
Jonathan S. Shapiro
shap at eros-os.org
Sat Feb 18 22:07:27 EST 2006
There is a major problem in Section 2.1
In my eagerness to maximize the protected payload, I took the EROS
capability representation, exchanged the allocation count and the key
data field, and the extended the key data slot to 24 bits. This gave me
(in Coyotos) a 32-bit protected payload and a 24-bit allocation count.
Unfortunately, I made a mistake in my haste: I neglected to allow room
for the "prepared" bit, which remains necessary. This is going to
require (at least) one more bit in the type code field.
There are two possible solutions:
1. Shrink the allocation count field to 20 bits, move the
permission bits out of the type code field, and put the
"prepared" bit into the type code byte (as it was in EROS)
2. Reserve the least significant bit of the OID field for this
My current inclination is to shrink the allocation count.
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