Date: Tue, 15 Nov 2022 10:58:04 -0700 From: Warner Losh <imp@bsdimp.com> To: sgk@troutmask.apl.washington.edu Cc: "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org> Subject: Re: Giant Locked drivers Message-ID: <CANCZdfo3VKyrQXx3-%2B52-XX53SbuMnDsXQhgb8GT=ZESaeyJ_w@mail.gmail.com> In-Reply-To: <Y3PR2GXR42LcdbDd@troutmask.apl.washington.edu> References: <CANCZdfrfNzb1O91T4ivMXPsUGu7mYX80pJxvQu07oe2AF=YXCw@mail.gmail.com> <Y3PR2GXR42LcdbDd@troutmask.apl.washington.edu>
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[-- Attachment #1 --] On Tue, Nov 15, 2022 at 10:52 AM Steve Kargl < sgk@troutmask.apl.washington.edu> wrote: > On Tue, Nov 15, 2022 at 10:37:36AM -0700, Warner Losh wrote: > > > > 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? > > > > Is there a list of effected drivers? Grepping /var/run/dmesg.boot > on my system shows only "atkbd0: [GIANT-LOCKED]". A scan of atkbd(4) > shows > > This driver is required for the console driver syscons(4) or vt(4). > > So, setting debug.giant_drivers=1 will brick all FreeBSD workstations? > You could still access them via serial port or the network. And I think USB-based systems would be fine. The comment you quoted is slightly overstated. And yes, the point is to show the pain and get people to get off their !$#^ and do something if they care. Warner [-- Attachment #2 --] <div dir="ltr"><div dir="ltr"><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Nov 15, 2022 at 10:52 AM Steve Kargl <<a href="mailto:sgk@troutmask.apl.washington.edu">sgk@troutmask.apl.washington.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">On Tue, Nov 15, 2022 at 10:37:36AM -0700, Warner Losh wrote:<br> > <br> > It's no secret fiant-locked drivers' days are numbered. We've been more<br> > sluggish about eliminating Giant than had been hoped. I plan in the coming<br> > weeks to add a tunable 'debug.giant_drivers' which initially will be set to<br> > enable/disable giant-locked drivers in the tree.<br> > <br> > When set to 0, you get today's behavior. If set to 1, it will no longer<br> > allow drivers that don't request MPSAFE interrupt handlers from registering<br> > (the interrupt setup will return an error).<br> > <br> > This will allow us to understand what is lost if we throw the switch, and<br> > allow users to proactively test their systems to see if they are<br> > affected or not (and if they are, if they want to live without the<br> > functionality, or want to fund work in the area).<br> > <br> > Comments?<br> > <br> <br> Is there a list of effected drivers? Grepping /var/run/dmesg.boot<br> on my system shows only "atkbd0: [GIANT-LOCKED]". A scan of atkbd(4)<br> shows<br> <br> This driver is required for the console driver syscons(4) or vt(4).<br> <br> So, setting debug.giant_drivers=1 will brick all FreeBSD workstations?<br></blockquote><div><br></div><div>You could still access them via serial port or the network.</div><div><br></div><div>And I think USB-based systems would be fine. The comment you quoted is slightly overstated.</div><div><br></div><div>And yes, the point is to show the pain and get people to get off their !$#^ and do something if they care.</div><div><br></div><div>Warner</div></div></div>
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