Date: Fri, 30 Aug 2019 09:06:38 -0700 From: John Baldwin <jhb@FreeBSD.org> To: Eugene Grosbein <eugen@grosbein.net>, Bruce Evans <brde@optusnet.com.au> Cc: Freebsd hackers list <freebsd-hackers@freebsd.org> Subject: Re: FreeBSD Security Advisory FreeBSD-SA-19:23.midi Message-ID: <a3977237-3f24-ecb9-4399-c8d8fedc26ea@FreeBSD.org> In-Reply-To: <5961a5af-d36c-4b8f-20c1-e7054b0149f4@grosbein.net> References: <20190820201257.7A9D41F8B7@freefall.freebsd.org> <f19d3f62-940c-7888-b379-f416dfc45cac@grosbein.net> <20190830133855.W1405@besplex.bde.org> <5961a5af-d36c-4b8f-20c1-e7054b0149f4@grosbein.net>
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On 8/30/19 12:56 AM, Eugene Grosbein wrote: > 30.08.2019 11:03, Bruce Evans wrote: > >> The patch preserves some historical mistakes and adds some excessive >> verboseness about probe failures. I'm still waiting for jhb to reply to >> mails on 30 Oct 2015 and 23 Jan 2018 asking for a review of this patch >> or better a complete fix. > > Hmm... Maybe additional notification worth it :-) Hmm, I've used 'hint.foo.0.disabled=1' with many devices and it works fine. devctl enable can "undo" the disable post-boot even. It doesn't disable probing, only attaching once we know which driver a device is going to use. As far as I can tell, the patch makes it disable DEVICE_PROBE as well, but the vast majority of DEVICE_PROBE routines are idempotent. Only a handful of legacy ISA drivers use 'return (0)' to try to pass state from probe to attach via the softc. Those drivers could choose to check the disabled flag in their probe routine and/or be fixed to have idempotent probe routines. I think the latter is probably the best path forward. -- John Baldwin
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