On Thu, May 11, 2017 at 01:35:28PM +0200, Paolo Bonzini wrote: > Ignore env->a20_mask when running in system management mode.
Thanks Paolo. I don't think this patch will help SeaBIOS though. The SeaBIOS SMM handler doesn't do much - it doesn't even access ram above 1MiB. See SeaBIOS' code in src/fw/smm.c:handle_smi(). Instead, the SeaBIOS code does a cpu state backup/restore to switch into 32bit mode. I thought the A20 state would be part of that cpu backup/restore. However, looking at the Intel SDM docs now, it's not really clear to me how the processor "inhibits" A20 when in SMM mode - does it save/restore that state on SMI/RSM or does it have special logic to ignore A20 while in SMM mode? -Kevin
