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Date:      Tue, 15 Nov 2022 10:37:36 -0700
From:      Warner Losh <imp@bsdimp.com>
To:        "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org>
Subject:   Giant Locked drivers
Message-ID:  <CANCZdfrfNzb1O91T4ivMXPsUGu7mYX80pJxvQu07oe2AF=YXCw@mail.gmail.com>

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Greetings,

It's no secret fiant-locked drivers' days are numbered. We've been more
sluggish about eliminating Giant than had been hoped. I plan in the coming
weeks to add a tunable 'debug.giant_drivers' which initially will be set to
enable/disable giant-locked drivers in the tree.

When set to 0, you get today's behavior. If set to 1, it will no longer
allow drivers that don't request MPSAFE interrupt handlers from registering
(the interrupt setup will return an error).

This will allow us to understand what is lost if we throw the switch, and
allow users to proactively test their systems to see if they are
affected or not (and if they are, if they want to live without the
functionality, or want to fund work in the area).

Comments?

Warner

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<div dir=3D"ltr">Greetings,<div><br></div><div>It&#39;s no secret fiant-loc=
ked drivers&#39; days are numbered. We&#39;ve been more sluggish about elim=
inating Giant than had been hoped. I plan in the coming weeks to add a tuna=
ble &#39;debug.giant_drivers&#39; which initially will be set to enable/dis=
able giant-locked drivers in the tree.</div><div><br></div><div><div>When s=
et to 0, you get today&#39;s behavior. If set to 1, it will no longer allow=
 drivers that don&#39;t request MPSAFE interrupt handlers=C2=A0from registe=
ring (the interrupt setup will return an error).</div><div><br></div><div>T=
his will allow us to understand what is lost if we throw the switch, and al=
low users to proactively=C2=A0test their systems to see if they are affecte=
d=C2=A0or not (and if they are, if they want to live without the functional=
ity, or want to fund work in the area).</div><div><br></div><div>Comments?<=
/div><div><br></div><div>Warner</div></div></div>

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