Hi Matt, > -----Original Message----- > From: Matt Fleming [mailto:matt@xxxxxxxxxxxxxxxxxxx] > Sent: Wednesday, March 09, 2016 11:35 PM > To: Chen, Yu C > Cc: Rafael J. Wysocki; Rafael J. Wysocki; ACPI Devel Maling List; > x86@xxxxxxxxxx; linux-efi@xxxxxxxxxxxxxxx; Linux Kernel Mailing List; linux- > pm@xxxxxxxxxxxxxxx; Len Brown; Thomas Gleixner; Ingo Molnar; H. Peter > Anvin; Zhang, Rui > Subject: Re: [PATCH][RFC v3] ACPI / PM: Fix poweroff issue on HW-full > platforms without _S5 > > On Tue, 08 Mar, at 04:25:30PM, Chen, Yu C wrote: > > Hum. unfortunately it is not guaranteed to run after all of the other > > code, because other components who register pm_power_off may be > built as modules, and > > we can not predict/control the sequence registration. So this patch may > > break the EFI platforms who use non-efi poweroff due to unstable EFI > > service , not sure if there are any released-products of this kind. > > Certainly the majority of x86 client machines do not use EFI power off, > because it hardly ever functions correctly. > > > Currently I'm thinking of 3 possible solutions, could you please give some > advices on them: > > > > 1. Introduce bootopt of 'poweroff=efi' > > Set the pm_power_off to efi_power_off no matter whether there is > > _S5 or not > > > > 2. Introduce /sys/power/poweroff > > Allow the user to choose which pm_power_off, for example: > > > > # cat /sys/power/poweroff > > *acpi acpi_power_off > > efi efi_power_off > > gpio gpio_poweroff_do_poweroff > > user can echo string to enable which one. > > > > And two APIs: > > register_power_off(char *name, power_off func) > > unregister_power_off(char *name) > > > > > > 3. replace all the codes of pm_power_off() with > > reliable_pm_power_off() > > > > void reliable_pm_power_off(void) > > { > > if (!pm_power_off) { > > if (acpi_no_s5) > > pm_power_off = efi_power_off; > > /* Other conditions added in the future. */ > > } > > pm_power_off(); > > } > > Be wary of adding all these control knobs. People just want their machines to > reboot properly without having to mess with boot parameters. > > Let's go back to the start. What prompted this patch? Do Intel have (or are > planning) machines that do not have _S5 and are expected to use EFI to reset > the system? Yes, there might be a new platform without _S5, and might need EFI poweroff for a backup. > Or is this some new configuration discussed in the ACPI spec > that Linux needs to be support? > > Can we remove the ambiguity and options to force EFI reset if _S5 is missing? > Afterall, that's why the function is called efi_poweroff_*required*. OK, the boot option is obsoleted, I'll try another version of default_power_off per Rafael's suggestion, thanks. yu -- 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
