Re: [PATCH v2 2/3] PCI: Allow specifying devices using a base bus and path of devfns

[Andy Shevchenko <andy.shevchenko@gmail.com>]

On Fri, Jun 1, 2018 at 2:50 AM, Logan Gunthorpe <logang@deltatee.com> wrote:
> When specifying PCI devices on the kernel command line using a
> BDF, the bus numbers can change when adding or replacing a device,
> changing motherboard firmware, or applying kernel parameters like
> pci=assign-buses. When this happens, it is usually undesirable to
> apply whatever command line tweak to the wrong device.
>
> Therefore, it is useful to be able to specify devices with a base
> bus number and the path of devfns needed to get to it. (Similar to
> the "device scope" structure in the Intel VT-d spec, Section 8.3.1.)
>
> Thus, we add an option to specify devices in the following format:
>
> path:[<domain>:]<bus>:<slot>.<func>/<slot>.<func>[/ ...]
>
> The path can be any segment within the PCI hierarchy of any length and
> determined through the use of 'lspci -t'. When specified this way, it is
> less likely that a renumbered bus will result in a valid device specification
> and the tweak won't be applied to the wrong device.
>
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> Reviewed-by: Stephen Bates <sbates@raithlin.com>
> Acked-by: Christian König <christian.koenig@amd.com>

> -                               specified in one of two formats:
> +                               specified in one of three formats:

...in one of the following formats:

in the first place and don't fix it each time you add/remove one?


-- 
With Best Regards,
Andy Shevchenko