On Thu, Feb 12, 2009 at 06:24:29PM +0000, Tim Small wrote: > Bjorn Helgaas wrote: > >Does it have more details > >about why they recommend it be disabled? Presumably they'd like to > >have the EDAC functionality (maybe on Windows?), so I would think that > >they'd only recommend disabling the device if it were broken or there > >were some other avenue for supporting EDAC. > My understanding is that since EDAC drivers have been missing from OS > for so long (the only one I've ever seen is a Compaq written one for > Windows in Pentium-II era machines), that they believe that EDAC > functionality should be the job of the BIOS, and thus hidden from the OS... It might be that Intel did not trust the OS writers enough to not do stupid things with memory controller settings. ;) > However... Most BIOS level support is deficient in some way (e.g. > poor/no error reporting mechanisms / no uniform way to enable / just > plain doesn't exist or work / accesses PCI registers from System > Management Mode, in an unsafe way WRT what Linux might already be doing). > > Obviously, racing with the BIOS for access to these registers is a bad > thing, and this issue was raised on LKML a few years ago: > > http://lkml.indiana.edu/hypermail/linux/kernel/0604.3/0107.html > > Michał: Are the chipset registers set up to trigger an SMI when an ECC > error occurs? If so, you probably need to disable that as well with > this patch - otherwise you might never get to see the errors in the EDAC > driver anyway... i865 does not support ECC but has otherwise compatible register layout to i875. I made this patch because I wanted to find out what my BIOS is doing wrong when I put two not-really-matching DIMMs but got distracted with another BIOS misbehaviour (WiFi card lock-out). > Is it legitimate to unhide this device? I think probably yes, but you > have to be pretty sure that you're not going to fight with the BIOS over > access to the relevant registers. OpenBIOS? LinuxBIOS? If the flash chip in my laptop was easily replaceable I would be trying to run coreboot (formerly LinuxBIOS) by now. :) Best Regards, Michał Mirosław -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
