On Tue, Jul 03, 2007 at 03:17:35PM -0700, Kamal gupta wrote: > Hi > > I got the answers to most of my questions except one thing. Would be glad if > anyone can give some hint. > > Here is what I understood (very briefly), please feel free to point out if I > am wrong: What specifically are you looking to understand here? PCI device and bus initialization or the more "generic" driver core bus and driver interaction? They are two separate things. > When system initializes, firmware scans for all the devices, Depends on the architecture. > assigns address regions and soon, Again, depends on the architecture. > then comes the driver registration phase where driver matching takes > place, which finally calls the probe function (which can reassign the > address regions, if wants to), No, it can't reassign pci address regions here, they are already fixed. > I think IRQ configuration takes place here only. No, that happens when you call pci_enable_irq(). > Once matched, we are done. Done with what? > Since it creates the id table in registration phase, these entries are > stored in /lib/modules/KERNEL_NAME/modules.pcimap for user space hot > plugging. No, no one uses those tables anymore, they are still there for backward compatiblity with 2.4 kernels. We should delete them soon. > When ever system detects the new device, kobject_hotplug invokes > call_usermodehelper which invokes /sbin/hotplug with a input parameter > PCI and environment variable describing the device. This /sbin/hotplug > program then do the matching and we are done. Not really, all that callout does is call 'modprobe' with the module alias given to it by the kernel, which then walks the list of module aliases and loads all modules that match. Then the kernel does the matching of driver to device with the call to the individual driver probe() functions until it finds a match. > My question is, I looked at the probe.c whose functions (scan slot and scan > bus) are used by the hotplug directory. I think what is happening here is, > each of the core files define enable slot function which configures the > device and use the functions in probe file. Then there is top file, > pci_hotplug_core which calls this enable slot in power_write_file function. > Can anyone please explain what is happening here ? and if hot-plugging is > there via /sbin/hotplug ? why this ? Ok, I think you are getting PCI hotplug mixed up with the more generic function of just loading and binding pci drivers to devices. PCI hotplug is to enable and disable PCI devices at runtime, if you have the special hardware to allow this to happen. These drivers control the special hardware to do this. > PS: Potentially, there is no device initialization phase for PCI (unlike > net_dev_init defined in *net/core/dev.c*), since firmware BIOS already did > that stuff. Am I right ? I do not understand the question. Again, what specifically are you trying to understand here? thanks, greg k-h -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
