Re: Getting IOCTL's into VFS File System Drivers

H. Peter Anvin (hpa@transmeta.com)
14 Nov 1999 18:17:48 GMT

Followup to: <7Ss55F9mw-B@khms.westfalen.de>
By author: kaih@khms.westfalen.de (Kai Henningsen)
In newsgroup: linux.dev.kernel
>
> > Obviously modeled after v7, but _what_ a mess had they slapped onto
> > the upper half for CP/M emulation... Scary. It almost looked like a small
> > subset of UNIX placed on a box with rather shitty IO and buried under the
> > heaploads of CP/M compatibility crap. They might start with CP/M clone,
> > but 3.x internals looked rather like a castrated and mutilated Xenix.
>
> That was true since 2.x, actually, and what they mutilated was Xenix. It
> was officially called "Xenix compatibility".
>
> There is a persistent rumour that the "\" thing was because one of the
> developers simply got things wrong by accident.
>

And it is also obviously bull. DOS 1.x (which was a pure CP/M clone)
used / as the option character, so for compatibility they couldn't use
it for paths... *especially* since DOS made it legal to type the
option immediately adjacent to a pathname (COPY FOO BAR/V). DOS 2.x
actually had an option to use - as the option character, which made it
possible to use / as a pathname separator. DOS 2.x also had a kernel
option to only recognize devices if the path was prepended with \DEV\
(or /DEV/), instead of polluting the namespace of every single
directory. I believe OS/2 actually used this.

To this day, every version of DOS 2.0 and later allows you to use / as
the pathname separator in system calls -- but most utilities will see
it as an option marker.)

-hpa

-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."


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