Date: Sat, 3 Jan 2015 09:31:22 -0800 From: Alfred Perlstein <bright@mu.org> To: Adrian Chadd <adrian@freebsd.org> Cc: "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org> Subject: Re: odd behaviour with graphics, vt(4), VGA, and probing the text region leading to NMIs at boot Message-ID: <2F715AD9-CF34-4516-B75E-E14C77BFD2E3@mu.org> In-Reply-To: <CAJ-Vmon2BZZbMRAJVAN=cngZmqu8XRQ8LzswqETsfwrLmfB53w@mail.gmail.com> References: <CAJ-Vmon2BZZbMRAJVAN=cngZmqu8XRQ8LzswqETsfwrLmfB53w@mail.gmail.com>
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Sounds like the virtualization code is sensitive to the mode. Meaning = that whatever is virtualizing the graphics card doesn't do the proper = thing when you're in a graphical mode. Can't the probes be turned off? Basically when the "card" is in gfx mode, it doesn't do the right thing = for those memory addresses. Sounds like the fix would be to not touch = those regions unless you're actually in text mode. =20 On Jan 3, 2015, at 9:12 AM, Adrian Chadd wrote: > Hi, >=20 > I found -head didn't boot on a T400 I have here with external radeon > graphics (ie, not using the intel graphics.) >=20 > I was getting a memory parity error NMI upon boot, shortly after > probing option ROMs. >=20 > It turns out that it's the ISA device probe/attach path trying to > attach the VGA adapter, and doing testing of the memory regions at > 0xb800:0000 (mono text) and 0xb000:0000 (colour text) - yes, I'm using > the 8086 real mode notation because I'm talking about ISA graphics > cards. >=20 > If I boot -HEAD with vt(4) in graphics mode, then it's using 640x480 > graphics and that's mapped at 0xa000:0000 for 64k. There apparently > isn't anything at 0xb800:0000 or 0xb000:0000 and touching those > regions leads to an NMI. >=20 > Now, the tricksy bit is that it's not accessing those addresses > directly - it's going via the physical map, that's mapped it at > 0xc00b8000 and 0xc00b0000 - yes, those are 32 bit (virtual, kernel > mode) addresses. I don't know if this is part of the problem. >=20 > If I boot -HEAD with vt(4) in text mode (hw.vga.textmode=3D1) then it = boots fine. >=20 > So - has anyone else seen/debugged this? It doesn't happen on > everything - just this one T400 I have. But I can't help but wonder > what else is going to get finnicky about ISA probing like this. > _______________________________________________ > freebsd-arch@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-arch > To unsubscribe, send any mail to = "freebsd-arch-unsubscribe@freebsd.org" >=20
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