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SubjectHot PCI bus plugging

There is little operational difference between hot-swap PCI and CardBus.
And some of us have been be working with CardBus devices for years.
For instance, see
http://cesdis.gsfc.nasa.gov/linux/drivers/kern-2.3/index.html

If you consider the issues, CardBus is actually a more difficult
environment. The driver must contend with switching between two
incompatible signaling schemes (PCMCIA is ISA-like), reading an overly
complicated CIS, setting the voltages and timings according to what was read
from the CIS, and rapid insert/eject cycles(*).

Both hot-swap PCI and CardBus require multiple logical bus bridges that can
disconnect the signal leads and turn off power to just one slot, so don't
try hot-plugging cards on your standard desktop machine!


* IBM's hot-swap implementation sends an "eject" signal when you pivot the
PCI card hold-down. There is plenty of time before the card is removed. In
contrast, CardBus drivers must deal with the card going away without
warning, or a barely-inserted card that is activated many times a second.

Donald Becker Scyld Computing Corporation
becker@tidalwave.net
240-463-0035 (voice) Columbia MD


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