sysfs-pci remove

sysfs-pci remove

[ratheesh kannoth]

Hi list,

https://www.kernel.org/doc/Documentation/filesystems/sysfs-pci.txt
talks about "remove" entry.
The 'remove' file is used to remove the PCI device, by writing a non-zero
integer to the file.  if i remove the device , will the bar resource
map still appear on /proc/iomem ?


-Ratheesh

Re: sysfs-pci remove

[Yijing Wang]

On 2014/12/17 1:51, ratheesh kannoth wrote:
> Hi list,
> 
> https://www.kernel.org/doc/Documentation/filesystems/sysfs-pci.txt
> talks about "remove" entry.
> The 'remove' file is used to remove the PCI device, by writing a non-zero
> integer to the file.  if i remove the device , will the bar resource
> map still appear on /proc/iomem ?

Of course not.

> 
> 
> -Ratheesh
> --
> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> 


-- 
Thanks!
Yijing

Re: sysfs-pci remove

[ratheesh kannoth]

I could see the pci resource in /proc/iomem.

But , lspci -s 06:0.0 -vv  shows that there is no kernel mode driver
for that interface.


On Wed, Dec 17, 2014 at 6:30 AM, Yijing Wang <wangyijing@huawei.com> wrote:
> On 2014/12/17 1:51, ratheesh kannoth wrote:
>> Hi list,
>>
>> https://www.kernel.org/doc/Documentation/filesystems/sysfs-pci.txt
>> talks about "remove" entry.
>> The 'remove' file is used to remove the PCI device, by writing a non-zero
>> integer to the file.  if i remove the device , will the bar resource
>> map still appear on /proc/iomem ?
>
> Of course not.
>
>>
>>
>> -Ratheesh
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>>
>
>
> --
> Thanks!
> Yijing
>

Re: sysfs-pci remove

[Yijing Wang]

On 2014/12/17 13:21, ratheesh kannoth wrote:
> I could see the pci resource in /proc/iomem.
> 
> But , lspci -s 06:0.0 -vv  shows that there is no kernel mode driver
> for that interface.

If the device 06:0.0 was removed by "echo 1 > /sys/.../0000:6:0.0/remove",
you could not see lspci info for this device anymore.
Do you really remove the device ?

> 
> 
> On Wed, Dec 17, 2014 at 6:30 AM, Yijing Wang <wangyijing@huawei.com> wrote:
>> On 2014/12/17 1:51, ratheesh kannoth wrote:
>>> Hi list,
>>>
>>> https://www.kernel.org/doc/Documentation/filesystems/sysfs-pci.txt
>>> talks about "remove" entry.
>>> The 'remove' file is used to remove the PCI device, by writing a non-zero
>>> integer to the file.  if i remove the device , will the bar resource
>>> map still appear on /proc/iomem ?
>>
>> Of course not.
>>
>>>
>>>
>>> -Ratheesh
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
>>> the body of a message to majordomo@vger.kernel.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>
>>>
>>
>>
>> --
>> Thanks!
>> Yijing
>>
> 
> 


-- 
Thanks!
Yijing

Re: sysfs-pci remove

[ratheesh kannoth]

On Wed, Dec 17, 2014 at 11:20 AM, Yijing Wang <wangyijing@huawei.com> wrote:
> If the device 06:0.0 was removed by "echo 1 > /sys/.../0000:6:0.0/remove",
> you could not see lspci info for this device anymore.
> Do you really remove the device ?

Oh , my bad. I did not remove the device. I did an unbind

 echo -n "0000:06:00.0" > /sys/bus/pci/drivers/enic/unbind0

Unbind wont remove it from /proc/iomem ? I thought enic pci driver is
the one is calling ioremap on those memory ?

Thanks,
Ratheesh

Re: sysfs-pci remove

[Yijing Wang]

On 2014/12/17 14:08, ratheesh kannoth wrote:
> On Wed, Dec 17, 2014 at 11:20 AM, Yijing Wang <wangyijing@huawei.com> wrote:
>> If the device 06:0.0 was removed by "echo 1 > /sys/.../0000:6:0.0/remove",
>> you could not see lspci info for this device anymore.
>> Do you really remove the device ?
> 
> Oh , my bad. I did not remove the device. I did an unbind
> 
>  echo -n "0000:06:00.0" > /sys/bus/pci/drivers/enic/unbind0
> 
> Unbind wont remove it from /proc/iomem ? I thought enic pci driver is
> the one is calling ioremap on those memory ?

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.

> 
> Thanks,
> Ratheesh
> 
> 


-- 
Thanks!
Yijing

Re: sysfs-pci remove

[ratheesh kannoth]

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 ?

Thanks,
Ratheesh

Re: sysfs-pci remove

[Yijing Wang]

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()

> 
> Thanks,
> Ratheesh
> --
> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> 


-- 
Thanks!
Yijing

Re: sysfs-pci remove

[Bjorn Helgaas]

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.

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

Re: sysfs-pci remove

[Yijing Wang]

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