Messages in this thread | | | Subject | Re: [PARPORT] [patch] lp needed testers [Re: lp fix against pre-2.1.127-7] | Date | Fri, 06 Nov 1998 22:46:51 +0100 | From | Philip Blundell <> |
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>+ * Obsoleted the CAREFUL flag since a printer that doesn' t work with >+ * CAREFUL will block a bit after in lp_check_status().
Can you explain this a bit more?
>+ /* >+ * Be sure that the CPU doesn' t reorder instructions. >+ * I am not sure if it' s needed also before an outb(). >+ * If not tell me ;-). -arca >+ */ >+ mb();
An mb() stops the *compiler* from re-ordering things. It doesn't generate any actual code and so the CPU never sees it. I'm fairly sure that inb() and outb() are volatile themselves and don't need additional optimisation barriers.
Did adding this mb() fix a problem?
p.
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