Date: Sun, 14 Jan 1996 19:12:09 +1100 From: Bruce Evans <bde@zeta.org.au> To: bugs@FreeBSD.ORG, geert@sun3.iaf.nl Subject: Re: ATI Mach-64 problems in Textmode!!! Message-ID: <199601140812.TAA27651@godzilla.zeta.org.au>
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>There is a bug in FreeBSD which leads to unexpected conflicts between >serial ports and the ATI Mach-64 Xpression PCI-based video card: the >FreeBSD kernel writes to the IO-port at address 0x2ec when it shouldn't, >resulting in a black screen during kernel load. This was fixed in FreeBSD-current on 1995/11/29. It should be fixed in FreeBSD-stable soon. >I experienced the bug using FreeBSD-v2.05, but I got mail from other >users who had the same problem with FreeBSD-v2.1. There is a workaround >for this bug, but it's not trivial and should be included in the FAQ. I'm not sure how the FAQ should cover old versions. People with old versions of the system often have old versions of the FAQ, and its hard to provide a different answer for each version. For -current, the FAQ might be: Q: Why does my sio1 sometimes fail after rebooting? A: It depends. Perhaps you have an sio3 port on the same interrupt as sio1. Due to the ISA bus's inability to share interrupts, full initialization of sio1 requires partial initialization of sio3. The standard sio ports (sio0-sio3) used to be partially initialized if any one of them is configured (whether or not one is physically present). This is no longer done because it caused problems with nonstandard graphics cards at the same address as sio3. Now you must configure and enable sio3 if it shares the same interrupt as sio1 _even if FreeBSD won't be able to use it because of the interrupt conflict_. Version-dependent parts of answer: 1: The above only applies for -current after 1195/11/23. 2: The above doesn't actually apply for the GENERIC configuration. It still configures and enables sio3. It should configure but disable sio3. 3: config(8) doesn't support disabling, so GENERIC will have to leave sio3 unconfigured. Q: How can I use sio3 to install? A: For version XXX, boot with -c and steal a configured sio port... For version YYY, boot with -c and enable sio3. (Xref to braindamage for ISA interrupts, S3 graphics cards, historical PC configuration and the current FreeBSD config(8) for why this isn't the default.) Bruce
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