Date: Thu, 05 Mar 2009 01:26:29 -0600 From: Robert Noland <rnoland@FreeBSD.org> To: Scott Long <scottl@samsco.org> Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org, "M. Warner Losh" <imp@bsdimp.com> Subject: Re: svn commit: r189367 - head/sys/dev/pci Message-ID: <1236237989.1384.34.camel@widget.2hip.net> In-Reply-To: <49AF6393.6060402@samsco.org> References: <1236218572.1384.19.camel@widget.2hip.net> <20090304.194158.1159134197.imp@bsdimp.com> <1236224629.1384.22.camel@widget.2hip.net> <20090304.210322.1353606728.imp@bsdimp.com> <49AF6393.6060402@samsco.org>
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--=-Twpvwl4HYjM/MkyK6pdr Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Wed, 2009-03-04 at 22:30 -0700, Scott Long wrote: > M. Warner Losh wrote: > > In message: <1236224629.1384.22.camel@widget.2hip.net> > > Robert Noland <rnoland@FreeBSD.org> writes: > > : On Wed, 2009-03-04 at 19:41 -0700, M. Warner Losh wrote: > > : > In message: <1236218572.1384.19.camel@widget.2hip.net> > > : > Robert Noland <rnoland@FreeBSD.org> writes: > > : > : On Wed, 2009-03-04 at 13:56 -0700, M. Warner Losh wrote: > > : > : > In message: <200903041823.n24INmcc049524@svn.freebsd.org> > > : > : > Robert Noland <rnoland@freebsd.org> writes: > > : > : > : Author: rnoland > > : > : > : Date: Wed Mar 4 18:23:48 2009 > > : > : > : New Revision: 189367 > > : > : > : URL: http://svn.freebsd.org/changeset/base/189367 > > : > : > :=20 > > : > : > : Log: > > : > : > : Extend the management of PCIM_CMD_INTxDIS. > > : > : > : =20 > > : > : > : We now explicitly enable INTx during bus_setup_intr() if it= is needed. > > : > : > : Several of the ata drivers were managing this bit internall= y. This is > > : > : > : better handled in pci and it should work for all drivers no= w. > > : > : > : =20 > > : > : > : We also mask INTx during bus_teardown_intr() by setting thi= s bit. > > : > : > : =20 > > : > : > : Reviewed by: jhb > > : > : > : MFC after: 3 days > > : > : >=20 > > : > : > Note: the INTxDIS bit is new in PCI 3.0, and has no effect on e= arlier > > : > : > devices. This should be highlighted in the comments somewhere.= .. > > : > :=20 > > : > : It is documented in 2.3 as well, I'm not sure about previous vers= ions of > > : > : the spec though. > > : >=20 > > : > It isn't in 2.2, and even after 2.3 it is "optional". > > :=20 > > : The bit should be unused if it isn't supported by a given piece of > > : hardware. If it doesn't do anything, we are no worse off than before= . > > : I don't think this will cause any harm, only goodness when it is > > : supported. > >=20 > > Yes. I agree. This is just the sort of bit, however, that people > > looking for an interrupt storm would latch on to as being just the > > ticket... Which is why I suggested a comment... >=20 > Well, the other risk is that devices that claim strict PCI 2.0, 2.1, or > 2.2 compatibility might treat this bit as "undefined" and thus eligible > for a SERR condition, or even reassign it for proprietary use. I think > that this risk is small, but non-zero. I think that as long as we only > manipulate this bit in conjunction with MSI, we should be fine. But > yes, it must be stressed that this bit is not some magical cure-all for > interrupt storms, nor is it an appropriate mechanism for handling > arbitrary interrupts in an interrupt handler. I'm happy to add a comment, I'm just not certain what that comment should be. I don't find where it is marked as optional in the 2.3 spec, though I do find the part about interrupt pins being optional... robert. > Scott --=20 Robert Noland <rnoland@FreeBSD.org> FreeBSD --=-Twpvwl4HYjM/MkyK6pdr Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.10 (FreeBSD) iEYEABECAAYFAkmvfqUACgkQM4TrQ4qfROPRRACghysoqwMzVHuQ6u5uwcOZIr1h ZFwAn2j+Ok2bJhxbziKRGoW5TpEQUC9P =SFlt -----END PGP SIGNATURE----- --=-Twpvwl4HYjM/MkyK6pdr--
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