Messages in this thread | | | Date | Tue, 23 Feb 1999 12:13:19 -0800 | From | David Hinds <> | Subject | Re: PCMCIA eject timings |
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> As I understand, currently cards may happen to talk to empty slot if > the card is taken out in the middle of long driver operation ?
Correct. The eject interrupt can't be fielded instantaneously.
> If it is not so, what is the mechanism that prevents it or what is > the best way to be 100% sure about card being in slot ?
What most drivers do is to ensure that all loops will eventually terminate regardless of whatever garbage a card's status registers may contain. For instance, it doesn't matter if you push a packet out to a nonexistent network interface, or read a packet that is half garbage: upper layers will cope. If they can't (say, a user ejects a SCSI adapter with mounted filesystems), then it is the user's fault. However, it is very bad if an interrupt handler loops on a status register value that is stuck at 0xff when a card is ejected.
Handling ejects gracefully is probably an impossible problem for the general case, but I think we handle it almost-always-gracefully with not much code crud.
-- Dave Hinds
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