Messages in this thread | | | Date | Thu, 30 Jul 1998 18:43:53 -0400 | From | Mark Lord <> | Subject | Re: FS Corruption in 2.1.109 (fwd) |
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Richard B. Johnson wrote: ... > Now we have UDMA (Ugly DMA). Once the chip is programmed, the > CPU is available for other uses while the DMA completes. Looking > at the sources, I see that the CPU is really just polling for
No, it is not polling for completion. Completion is signaled by a hardware interrupt, and the CPU is elsewhere until that happens.
> completion (yes, the interrupts are enabled so something else could > use the CPU). Any problem with locking, that could prevent these > I/O operations from being atomic can cause problems. > > Since enabling interrupts during the PIO operation was a bad_thing(tm),
On only a couple of systems (other than cmd640 and rz1000 systems). It is a Good Thing(tm) on all others. The default is "off" for safety.
-- mlord@pobox.com The (ex-)Linux IDE guy
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