Re: [PATCH] PCI: Add pci shutdown ability

[Alan Stern <stern@rowland.harvard.edu>]

On Wed, 11 May 2005, Vivek Goyal wrote:

> > I looked into the possibility of having the PCI core disable interrupt
> > generation and DMA on each new device as it is discovered.  Unfortunately
> > there is no dependable, universal way to do this for IRQs.  (A notable gap
> > in the original PCI specification, IMHO.)  
> 
> PCI specification 2.3 onwards, command register bit 10 can be used for
> disabling the interrupts from respective device. And the very reason for
> introducing this bit seems to be to not allow the device issue interrupts
> until a suitable driver for the device has been loaded. Have a look at
> following message.
> 
> http://www.pcisig.com/reflector/msg05302.html
> 
> Probably this feature can be used to disable the interrupts from the devices
> and enable these back when respective driver is loaded. This will resolve
> the problem of drivers not getting initialized in second kernel due to shared
> interrupts in kdump and reliability of capturing dump can be increased. 

That's good, and it's certainly a step in the right direction.  It won't
help with any pre-PCI-2.3 devices out there but it might be worth trying
to implement.

Alan Stern

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