Re: blocksizes

[mlelstv%serpens.de@localhost (Michael van Elst)]

tsutsui%ceres.dti.ne.jp@localhost (Izumi Tsutsui) writes:

>Disklabel in cd(4) requires hardware block size for partition offsets,

All disklabels use hardware block sizes. cd(4) is no exception.

>but it also uses DEV_BSIZE for sizes.

cd(4) uses DEV_BSIZE units to address blocks.

>Isn't it one example of inconsistent hacks?

No, this is a place where this is used consistently. Maybe
it becomes clear when treating the disk address not like
a way to access hardware but a way to specify the data
layout.
While these are related, it is not a 1:1 relationship.

>There is no "right" solution. We can fix the hack with hacks,
>or we can also redesign it. Someone[tm] should make a decision.
>That's all.

Yesterdays' redesign is todays' hacks. By chosing words you
already say what you consider a "wrong" solution.

So far I have heard about three models.

- use DEV_BSIZE addressing (that's what we have now, no changes)
- use byte addressing (almost the same, just a few bits more, requires
  minor changes to device drivers and other code).
- use native block addressing (what we left in 1994, requires significant
  changes to device drivers and minor changes to other code).

To me, none of this has significant advantages.

-- 
-- 
                                Michael van Elst
Internet: mlelstv%serpens.de@localhost
                                "A potential Snark may lurk in every tree."