在 2017/12/29 下午9:44, Borislav Petkov 写道: > On Fri, Dec 29, 2017 at 09:17:34PM +0800, Jia Zhang wrote: >> Namely, the end user has to make a BIOS update to uprev the microcode. > > Not quite: end user is dependent on the OEM to get a BIOS update. > > What is meant with early loading in this context is, to put the > microcode in the initrd so that it gets loaded very early during the > *kernel* boot. And early-initrd-based loading is the default method we > do microcode loading with, anyway.
Thanks for clarifying the terms. What I meant was the microcode update has to be launched in BIOS rather than late loading in linux runtime. But I'm not quite sure whether or not the early-initrd-based loading is affected. I used a shared BDW-EP machine with a rev of microcode less than 0x0b000021 and observed the late loading is prohibited. I attempted to remove the is_blacklisted() and observed a system hang with the late loading. Eventually I followed up the erratum and updated the microcode through BIOS update. It is impossible to downgrade the BIOS to recover the old rev of microcode for me to have a test with early-initrd-based loading. Anyway, is_blacklisted() initially was introduced by Borislav to prohibit late loading only, so the early-initrd-based loading seems to be OK. Thanks, Jia > > So the blacklisting is only for *late* loading, through the sysfs > trigger. Which is only there for historical reasons and for some > configurations. >
