Fine grained sync policy control (was: What I want in GNU OS)

Tim Oldham tjo at Fulcrum.BT.CO.UK
Sat Jul 8 02:52:33 AEST 1989


In article <18410 at mimsy.UUCP> chris at mimsy.UUCP (Chris Torek) writes:
>SysV has an open() flag that causes writes to be immediate.  Presumably
>this can also be set and cleared with fcntl(F_SETFL). [yes - Tim]

Not  a  correction,  but an addition and word of warning-ish. O_SYNC,  the
flag in question, is only defined in the SVID addendum (V.3).

The  word  of warning, at the risk of teaching grandma to suck eggs:  many
companies say "hey, we're SVID conformant". But check the SVID conformance
level. Sometimes it's without the addendum features. Even then, check  the
kernel extensions conformance, otherwise you might be in for a shock  when
you  come  to  use  things  like  ptrace(2). This is particularly true  of
systems that aren't derived from AT&T source, and just look like SysV *IX.

As  a  quick  question,  why  does  the  SVID  say that the sticky bit  is
`reserved'? Usually this means that "no, you're not allowed to use that  -
we're  going  to say what it's for later". They seem to mean "do what  you
want  to  with  this  bit",  which  is  usually described as  `undefined'.
Comments?

	Tim.
-- 
Tim Oldham      tjo at fulcrum.bt.co.uk  or  ...!mcvax!ukc!axion!fulcrum!tjo
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