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...
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...
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?
Tim.
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