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Re: blocksizes

mouse%Rodents-Montreal.ORG@localhost (der Mouse) writes:

>> fs_fsbtodb depends on the block size of the underlying medium.

>Does it? All you need to do is make a mental switch from thinking of
>fs_fsbtodb as "filesystem blocks to underlying device blocks" to
>thinking of it as "filesystem blocks to interchange blocks", where an
>"interchange block" is defined as 512 octets.

Indeed, my first ad-hoc solution was to do exactly that: create a
filesystem image that pretends to be created for 512 byte sectors.

But this would break compatibility with other systems and did break
userland code. After all, raw devices still require block aligned I/O
(and that's device blocks, not your interchange blocks).

>Given how non-512-byte-sector devices have historically had their
>drivers pretend they're 512-byte-sector devices,

Historically? Historically drivers were addressed in native sector
numbers (or even CHS coordinates on other systems). Everything
became 512-byte-sector devices when or shortly after NetBSD
imported the current SCSI framework.

                                Michael van Elst
                                "A potential Snark may lurk in every tree."

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