On 05/04/18 15:00, Boris Ostrovsky wrote: > On 04/05/2018 08:19 AM, Juergen Gross wrote: >> On 05/04/18 12:06, George Dunlap wrote: >> >>> Aren't there flags in the binary somewhere that could tell the >>> toolstack / Xen whether the kernel in question needs the RSDP table in >>> lowmem, or whether it can be put higher? >> Not really. Analyzing the binary whether it accesses the rsdp_addr in >> the start_info isn't the way to go, IMO. >> >> I've sent a patch to xen-devel adding a quirk flag to the domain's >> config to enable the admin special casing such an "old" kernel. > > Can we backport latest struct hvm_start_info changes (which bumped > interface version) to 4.11 and pass RSDP only for versions >=1? And this would help how? RSDP address is passed today, the kernel just doesn't read it. And how should Xen know which interface version the kernel is supporting? And Xen needs to know that in advance in order to place the RSDP in low memory in case the kernel isn't reading the RSDP address from start_info. Juergen