In message: <[EMAIL PROTECTED]>
"william wallace" <[EMAIL PROTECTED]> writes:
: On 5/20/06, Warner Losh <[EMAIL PROTECTED]> wrote:
: > From: "william wallace" <[EMAIL PROTECTED]>
: > Subject: Re: misc questions about the device&driver arch
: > Date: Sat, 20 May 2006 13:39:08 +0800
: >
: > > comparing the method array of pci_pci and cardbusbridge:
: > > what losts in pci bridge but exist in cardbusbridge:
: > > 1 card interface
: > > 2 power interface
: > > 3 some functions :
: > > 3ain bus interface
: > > (bus_driver_added, cbb_driver_added),
: > > (bus_child_detached, cbb_child_detached),
: > > (bus_child_present, cbb_child_present),
: > > 3b in device interface
: > > (device_detach, cbb_detach),
: > > what exists in pci bridge but losts in cardbusbridge:
: > > (pcib_route_interrupt, pcib_route_interrupt),
: > >
: > > not only that ,functions r very different eventhough they realize the
: > > same interface function template
: > > wooo，so long to go to hotplug pci
: >
: > Yes. The hardest part would be to create a pci hot swap bridge
: > driver. The interface for them tend to be underdocumented.
: >
: > The bus_child_present is important for detaching.
: >
: > Also, I think that we may need to start implementing a quiess method
: > to tell the drivers they are about to be removed. For hot plug PCI,
: > the model is that you quess the driver, the os tells you somehow it is
: > safe, and then you remove the card. The details vary (some system are
: > all in software, while others have a complicated interlock and LEDs),
: > but they are similar. Cardbus is harder in some ways because cards
: > leave unannounced (in fact, there's not a good way to announce a card
: > leaving, but there should be).
: >
: > Warner
: >
: > > On 5/20/06, Warner Losh <[EMAIL PROTECTED]> wrote:
: > >
: > > > Busses create devices to represent hardware in the system. The bus
: > > > then causes these devices to be probed and attached. This latter
: > > > usage is for those cases. As drivers are loaded these devices are
: > > > offered to the new (and old) drivers in the system.
: > > >
: > > > FreeBSD inherently dynamic in its device system. The hardest part of
: > > > adding hotplug support is programming the bridge. Adding new devices
: > > > to the tree is easy, but knowing when to add them is hard since you
: > > > have to write a bridge driver...
: > > >
: > > > Warner
: Prior to removing a card from the system, two things must occur:
:
: The device's driver must cease accessing the card.
:
: The card must cease generation transaction and interrupts.
:
: How this is accomplished is OS-specific, but the following must take place:
:
: The OS must stop issuing new requests to the device's driver or must
: instruct the driver to stop accepting new requests.
:
: The driver must terminate or complete all outstanding requests.
:
: The card must be disabled from generating interrupts or transactions.
:
: When the OS commands the driver to quiesce itself and its device, the
: OS must not expect the device to remain in the system (in other words,
: it could be removed and not replaced with a similar card).
:
: How to design and implement quiescing in freebsd?
device_quiesce? I have it in a p4 tree right now. Specifically, it
hooks up to the MOD_UNLOAD with a QUIESCE flag. The driver's
device_quiesce routine gets called, the driver sleeps there until it
knows that it is good, then returns to the caller. Then the driver's
detach routine can be called.
Warner
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