Le 7 mars 2011 à 06:36, Chris Murphy a écrit :
> [...]
>
> That's essentially the same result as on Linux with the block level device.
> (Raw/character devices went away some time ago with Linux 2.6, and /dev/sda
> is definitely block level.)
>
> Still, it's mysterious why there is such a big difference between /dev/disk0
> and /dev/rdisk0 on XNU...it doesn't seem they should be that different. There
> must be something else going on.
Hello Chris,
For what it is worth, the implementations of dd on Mac OS X and Linux aren't
the same: GNU coreutils for the latter, Berkeley for the former.
But in both cases, they end with similar system calls:
open("/dev/sda", ...)
open("/dev/disk0", ...)
open("/dev/rdisk0", ...)
So, it is at the kernel level that the interpretation of device nodes differ;
it could well be that, given the initial philosophy of Linux wrt disks, the
semantics of open("/dev/sda", ...) tends to be close to the one of
open("/dev/rdisk0", ...).
While trying to somewhat refresh my memories about those matters in Linux, I
encountered this one:
http://www.linuxsa.org.au/pipermail/linuxsa/2002-February/038793.html
HTH,
Axel
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