netdev - Re: [PATCH mlx5-next v7 0/4] Dynamically assign MSI-X vectors count

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Message-ID: <20210311203140.GP2356281@nvidia.com>
Date:   Thu, 11 Mar 2021 16:31:40 -0400
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Alexander Duyck <alexander.duyck@...il.com>,
        Leon Romanovsky <leon@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Saeed Mahameed <saeedm@...dia.com>,
        Leon Romanovsky <leonro@...dia.com>,
        Jakub Kicinski <kuba@...nel.org>,
        linux-pci <linux-pci@...r.kernel.org>,
        linux-rdma@...r.kernel.org, Netdev <netdev@...r.kernel.org>,
        Don Dutile <ddutile@...hat.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        "David S . Miller" <davem@...emloft.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH mlx5-next v7 0/4] Dynamically assign MSI-X vectors count

On Thu, Mar 11, 2021 at 12:17:29PM -0600, Bjorn Helgaas wrote:

> > In addition it still feels rather hacky to be modifying read-only PCIe
> > configuration space on the fly via a backdoor provided by the PF. It
> > almost feels like this should be some sort of quirk rather than a
> > standard feature for an SR-IOV VF.
> 
> I agree, I'm not 100% comfortable with modifying the read-only Table
> Size register.  Maybe there's another approach that would be better?
> It *is* nice that the current approach doesn't require changes in the
> VF driver.

Right, that is the whole point here - if we wanted to change every
driver we could do that in some other way. Changing the table size
register is the only way to keep existing drivers working.

Jason