On Thursday, June 16, 2011, Matthew Garrett wrote: > On Thu, Jun 16, 2011 at 08:40:11AM +0800, Huang Ying wrote: > > On 06/15/2011 08:17 PM, Matthew Garrett wrote: > > >> You means the "APEI Support" bit for standard UUID? Do you know which > > >> machine uses this bit? I can write the code, but I have no machine to > > >> test it. > > > > > > I have access to a Dell system that uses this. > > > > Great! Can you help us to test the code? > > Yup, no problem. > > > > Urgh. One machine I've looked at enables APEI if the WHEA _OSC call is > > > made, and then clears a flag if any other _OSC call is made. In that > > > specific case it doesn't seem to matter (the flag never actually gets > > > checked in any of the other codepaths), but it seems that the intention > > > is for the generic call to be made and the WHEA one to be made after > > > that. > > > > Yes. The WHEA call should be made after the generic one. Another > > situation is as follow: > > > > - Generic _OSC call without "APEI Support" bit is called (in > > acpi_bus_osc_support). > > > > - After some time, when we think it is good to turn on firmware first > > mode fully, usually after we checking HEST and initializing > > corresponding module, we make generic _OSC call with "APEI Support" bit > > to turn on firmware first mode fully in standard way. > > > > Is it a good idea to make generic _OSC call twice, one without "APEI > > Support" bit, the other with "APEI Support" bit? > > I think we probably need to make the HEST decision early, and use that > to decide how to make the generic call. Our experience has been that > many firmware vendors only expect _OSC to be called once with any given > UUID - multiple calls can result in unexpected behaviour. Not really, as long as the "query enable" bit is set. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
