Re: CD writing in future Linux (stirring up a hornets' nest)

From: Theodore Ts'o
Date: Fri Feb 10 2006 - 09:50:46 EST

On Fri, Feb 10, 2006 at 03:32:28PM +0100, Joerg Schilling wrote:
> > Chapter and verse, please?
> >
> > Can you please list the POSIX standard, section, and line number which
> > states that a particular device must always have the same st_rdev
> > across reboots, and hot plugs/unplugs?
> A particular file on the system must not change st_dev while the system
> is running.

1) File != device.

2) st_dev != st_rdev

3) The reference you specified says nothing about st_dev (or st_rdev)
being invariant while the system is runnning. Line number, please?

4) POSIX/SUS is very careful not to define what dev_t. Use of mknod to
create block/chracter devices, and depending on any properties of
dev_t is likely to get you into trouble.

5) The st_rdev of a particular file, like /dev/hda *does* remain
invariant. The device which it points to may change, but that's a
different matter --- and POSIX/SUS is very deliberately silent on your

THEREFORE, your claim that Linux's behaviour violates POSIX/SUS is
demonstrably false. Quod erat demonstratum.

- Ted
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