netdev - Re: [PATCH] ptp: ocp: don't allow on S390

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Message-ID: <20210816214103.w54pfwcuge4nqevw@bsd-mbp.dhcp.thefacebook.com>
Date:   Mon, 16 Aug 2021 14:41:03 -0700
From:   Jonathan Lemon <jonathan.lemon@...il.com>
To:     Randy Dunlap <rdunlap@...radead.org>
Cc:     netdev@...r.kernel.org, Richard Cochran <richardcochran@...il.com>
Subject: Re: [PATCH] ptp: ocp: don't allow on S390

On Mon, Aug 16, 2021 at 02:15:51PM -0700, Randy Dunlap wrote:
> On 8/16/21 2:09 PM, Jonathan Lemon wrote:
> > On Fri, Aug 13, 2021 at 01:30:26PM -0700, Randy Dunlap wrote:
> > > There is no 8250 serial on S390. See commit 1598e38c0770.
> > 
> > There's a 8250 serial device on the PCI card.   Its been
> > ages since I've worked on the architecture, but does S390
> > even support PCI?
> 
> Yes, it does.
> 
> > > Is this driver useful even without 8250 serial?
> > 
> > The FB timecard has an FPGA that will internally parse the
> > GNSS strings and correct the clock, so the PTP clock will
> > work even without the serial devices.
> > 
> > However, there are userspace tools which want to read the
> > GNSS signal (for holdolver and leap second indication),
> > which is why they are exposed.
> 
> So what do you recommend here?

Looking at 1598e38c0770, it appears the 8250 console is the 
problem.  Couldn't S390 be fenced by SERIAL_8250_CONSOLE, instead
of SERIAL_8250, which would make the 8250 driver available?

For now, just disabling the driver on S390 sounds reasonable.
-- 
Jonathan