On 06/16/2011 09:38 AM, 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. acpi_bus_osc_support is called via subsys_initcall. It is a little hard to do all checking before that. Is it possible to call acpi_bus_osc_support later? Best Regards, Huang Ying -- 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
