linux-kernel - Re: [PATCH 0/3] Support timer drivers as loadable modules

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Date:   Thu, 9 Feb 2023 11:50:49 -0800
From:   John Stultz <jstultz@...gle.com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     walter.chang@...iatek.com, Thomas Gleixner <tglx@...utronix.de>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        "Maciej W . Rozycki" <macro@...am.me.uk>,
        wsd_upstream@...iatek.com, stanley.chu@...iatek.com,
        Chun-hung.Wu@...iatek.com, Freddy.Hsin@...iatek.com,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH 0/3] Support timer drivers as loadable modules

On Thu, Feb 9, 2023 at 7:36 AM Daniel Lezcano <daniel.lezcano@...aro.org> wrote:
>
> On 08/02/2023 10:48, walter.chang@...iatek.com wrote:
> > From: Walter Chang <walter.chang@...iatek.com>
> >
> > This patch exports functions in kernel so that timer drivers,
> > such as timer-mediatek.c can become loadable modules in GKI.
>
> What for ?

In general, it's the same reason why modules exist: We want to be able
to support a wide array of devices with a single kernel, but we don't
want all devices to pay the memory cost of code that will never be
used there. So being able to support loading device-specific bits like
clocksources (along with other device specific logic) helps.
Obviously it still has to make sense, and others have raised concerns
of stability issues if the hardware support is needed before we can
get to module loading, but I think if this allows drivers (such as
timer-mediatek) to be loadable safely, I see it as beneficial.

(And as others pointed out:  this patch series is incomplete as it
doesn't modularize the timer-mediatek driver, which would be a prereq
to supporting it upstream)

thanks
-john