netdev - Re: [PATCH v3] vhost: disable for OABI

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Message-ID: <20200420101511-mutt-send-email-mst@kernel.org>
Date:   Mon, 20 Apr 2020 10:16:11 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     linux-kernel@...r.kernel.org, Ard Biesheuvel <ardb@...nel.org>,
        Richard Earnshaw <Richard.Earnshaw@....com>,
        Sudeep Dutt <sudeep.dutt@...el.com>,
        Ashutosh Dixit <ashutosh.dixit@...el.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jason Wang <jasowang@...hat.com>, netdev@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, kvm@...r.kernel.org
Subject: Re: [PATCH v3] vhost: disable for OABI

On Mon, Apr 20, 2020 at 01:29:09AM -0700, Christoph Hellwig wrote:
> On Thu, Apr 16, 2020 at 06:20:20PM -0400, Michael S. Tsirkin wrote:
> > vhost is currently broken on the some ARM configs.
> > 
> > The reason is that that uses apcs-gnu which is the ancient OABI that is been
> > deprecated for a long time.
> > 
> > Given that virtio support on such ancient systems is not needed in the
> > first place, let's just add something along the lines of
> > 
> > 	depends on !ARM || AEABI
> > 
> > to the virtio Kconfig declaration, and add a comment that it has to do
> > with struct member alignment.
> > 
> > Note: we can't make VHOST and VHOST_RING themselves have
> > a dependency since these are selected. Add a new symbol for that.
> 
> This description is horrible.  The only interesting thing for ARM OABI
> is that it has some strange padding rules, but that isn't something
> that can't be handled.   Please spend some time looking into the issue
> and add te proper __padded annotations, we've done that elsewhere in
> the kernel and it isn't too bad - in fact it helps understanding issues
> with implicit alignment.

Yes I have a patch queued to fix it. I wanted a minimal patch for this
release though.

> And even if you have a good reason not to fix vhost (which I think you
> don't have) this changelog is just utter crap, as it fails to mention
> what the problem with ARM OABI even is.

I'll tweak that, thanks!

-- 
MST