Re: [PATCH] usertools: fix bind failure from dpdk to kernel

["lihuisong (C)" <lihuisong@huawei.com>]

在 2022/8/5 23:35, Stephen Hemminger 写道:
> On Fri, 5 Aug 2022 11:10:22 +0800
> Huisong Li <lihuisong@huawei.com> wrote:
>
>> Currently, the steps for binding device from dpdk driver to kernel
>> driver is as follows:
>> echo $BDF > /sys/bus/pci/drivers/vfio-pci/unbind
>> echo $BDF > /sys/bus/pci/drivers/$kernel_driver/bind
>>
>> This steps cannot bind device from dpdk driver to kernel driver on
>> platform with kernel 5.19. The 'driver_override' must be specify
>> kernel driver before binding device to kernel driver.
>>
>> Fixes: 720b7a058260 ("usertools: fix device binding with kernel tools")
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Huisong Li <lihuisong@huawei.com>
> Not sure exactly what you did and why.
> The patch seems to just remove the check that the driver
> is in the set of dpdk_drivers.
> .
Currently, the end of the operation binding device from kernel driver to
dpdk driver write '\00' to driver_override file so as to this device can
be bound to any other driver. And perform following steps to
bind device dpdk driver to kernel driver:
echo $BDF > /sys/bus/pci/drivers/vfio-pci/unbind
echo $BDF > /sys/bus/pci/drivers/$kernel_driver/bind

However, due to the patch[1] merged into 5.19 kernel, 'driver_override'
in the pci_dev is no longer NULL by writing '\00' to driver_override file.
This causes PCI match device failure and the device will never be bound to
their kernel driver.

In 5.19 kernel, I found that dpdk-devbind.py need to write '\n' to
driver_override file if we want to bind divce to any other driver.
But I think it is not necessary to write empty to driver_override
file. After all, the device has only one kernel driver, and binding
to dpdk driver(like, vfio-pci) must specify driver_override.

[1] 23d99baf9d72 ("PCI: Use driver_set_override() instead of open-coding")