Re: Extended partition mapping wrong size
From: Phillip Susi
Date: Tue Apr 06 2010 - 09:58:54 EST
On 4/6/2010 7:47 AM, Karel Zak wrote:
> This is probably kernel bug. It's really insane that the extended
> pseudo partition overflows to the next logical partition.
> Please no. I think the size should not be more than 2 sectors (1024
> bytes). The current concept works for years and we have in userspace
> /etc/partitions parsers that use "if (blocks <= 1)" to detect
> extended partitions.
Could you elaborate a bit on this? What programs have such tests and
what would they do differently if it were larger?
> The other problem are mkfs programs, the space used for alignment
> could be 1MiB (or more) -- it's enough many mkfs programs.
What's wrong with that? If you REALLY want to, there's no reason you
can't create a tiny fs there. Then again, I could swear that once upon
a time the kernel simply did not bother creating a dev node for the
extended partition, and this seems to be a hack that was put in to make
it easy for LILO to install to one. Personally I'd prefer going back to
the old behavior of just not having a useless device there.
> BTW, Linux does not use this policy for the others nested partition
> tables (e.g. Solaris, BSD, Minix, ...). The extended dos partition
> table is exception. The primary partitions for the others nested PT
> are exported to the system with its real size :-)
Indeed, also the hidden space in the logical partitions is also not
exposed, otherwise you would have two dev nodes per logical partition.
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