netdev - Re: [PATCH net-next v2 4/9] gve: Add support for dma

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Message-ID: <CAL9ddJciz2MD8CYqdbFLhYCKFk=ouHzzEndQwmcfQ-UqNNgJxQ@mail.gmail.com>
Date:   Wed, 2 Sep 2020 11:42:37 -0700
From:   David Awogbemila <awogbemila@...gle.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, Catherine Sullivan <csully@...gle.com>,
        Yangchun Fu <yangchun@...gle.com>
Subject: Re: [PATCH net-next v2 4/9] gve: Add support for dma_mask register

On Tue, Sep 1, 2020 at 5:34 PM Jakub Kicinski <kuba@...nel.org> wrote:
>
> On Tue,  1 Sep 2020 14:51:44 -0700 David Awogbemila wrote:
> > From: Catherine Sullivan <csully@...gle.com>
> >
> > Add the dma_mask register and read it to set the dma_masks.
> > gve_alloc_page will alloc_page with:
> >  GFP_DMA if priv->dma_mask is 24,
> >  GFP_DMA32 if priv->dma_mask is 32.
>
> What about Andrew's request to CC someone who can review this for
> correctness?
I didn't realize I needed to CC someone. How may I find suitable reviewers?

>
> What's your use case here? Do you really have devices with 24bit
> addressing?
I don't think there is a specific 24-bit device in mind here, only
that we have seen 32-bit addressing use cases where the guest ran out
of SWIOTLB space and restricting to GFP_DMA32 helped.. so we thought
it would be natural for the driver to handle the 24 bit case in case
it ever came along.