Re: sysfs-pci remove

[Yijing Wang <wangyijing@huawei.com>]

On 2014/12/18 3:09, Bjorn Helgaas wrote:
> On Wed, Dec 17, 2014 at 12:36 AM, Yijing Wang <wangyijing@huawei.com> wrote:
>> On 2014/12/17 14:21, ratheesh kannoth wrote:
>>> On Wed, Dec 17, 2014 at 11:44 AM, Yijing Wang <wangyijing@huawei.com> wrote:
>>>> Unbind won't release PCI device bar resource, resources in /proc/iomem is the
>>>> physical address resource(added by request_resource()), if you iounmap the bar resource,
>>>> it won't change anything in /proc/iomem.
>>>
>>> who is calling request_resource() ...is it enic driver ?
>>
>> PCI core interface, E.g pci_bus_assign_resources()
> 
> Hi Ratheesh,
> 
> There are two things going on in /proc/iomem:
> 
> 1) The core should put all the hardware that responds to physical
> accesses in /proc/iomem.  These entries should be there regardless of
> whether we have a driver for the device.  These are used when
> assigning addresses to new devices, to make sure we don't assign the
> same address to two different devices.  These entries include RAM,
> ACPI tables, APICs, PCI host bridges, PCI MMCONFIG regions, PCI
> devices, etc.  It *should* also include address space consumed by
> other things like PNP and ACPI devices, but that is currently missing.
> 
> 2) Individual drivers claim address space they use to control their
> device, e.g., with pci_request_regions(), ioremap(), etc.  This puts
> an entry in /proc/iomem with the driver name on it.  A device may
> respond to several physical address regions, and a driver need not
> claim all of them, and it may even claim only part of a region.

Yes, exactly, I missed this.

> 
> So when you unbind a driver, you should see the second type of entry
> go away.  When you actually remove a device (hot-remove or sysfs
> remove), you should see the first type go away as well, which means
> there's no longer anything that will respond to that physical address
> space.
> 
> Bjorn
> 
> 


-- 
Thanks!
Yijing