On 2014/2/28 12:56, Matthew Garrett wrote: > On Fri, Feb 28, 2014 at 12:11:57PM +0800, Li, Aubrey wrote: >> This patch is to introduce BOOT_EFI and BOOT_CF9 in the reboot sequence >> loop, to fix the reboot problem on the known Intel Bay Trail-T based >> platform, for example, ASUS-T100 and Dell Venue 8/11 Pro. These >> platforms don't support ACPI reboot, we expect to call EFI runtime >> service to handle this case, and CF9 is an alternate after EFI. > > EFI reboot is still somewhat unreliable - it may be safe after the > recent patches to provide a 1:1 mapping.
So it's acceptable to put EFI in the default list. > CF9 is, as far as I know, not part of any spec, so it seems like a bad > idea to put it in the default list. Any hurt known if put it in the default list? > > What do the ACPI reboot vectors look like on these systems? Reset register address: 0xCF9 Value to cause reset: 0x6 > >> - * 3) If still alive, write to the ACPI reboot register again >> - * 4) If still alive, write to the keyboard controller again >> + * 3) If still alive, call EFI runtime service >> + * 4) If still alive, write to the PCI IO port 0xCF9 > > This is definitely incorrect. The ACPI write *must* occur twice in order > to be effective on various systems. EFI shouldn't be attempted until > after the second ACPI write. > Do we have any spec mentioned that? Thanks, -Aubrey -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
