> 'guest_validate_base' is currently called for three reasons: (1) in main.c > when using -B, (2) in main.c when using -R after mapping the reserved va > region, and (3) and when probing for a guest base in probe_guest_base. > > For case (1) I suppose things are pretty much the same -- we just need to > map the extra region when needed (e.g. for the ARM kernel helpers).
Yes. > For case (2) maybe we can do a probing similar to what I mentioned here > [1], but taking into account what you stated above and ensuring that the > probing finds a single region for the request va region size and any > needed extra stuff. Something like that, yes. I suspect there are better ways to implement it though. In principle your patch is making (2) a variant of (3). Instead of probing for the segments covered by the image we probe for the reserved regions (e.g. for ARM [0-reserved_va, 0xffff0000 - 0xffffffff]). A good implementation should automagically DTRT for both 32-bit and 64-bit hosts. > Case (3) is mostly the same as (2) but we are probing for a guest base with > a region size deduced from looking at the image we are loading. I suppose > it is still OK to map two regions here. The single region only applies to > -R? I'd say (3) is more similar to (1). There's no fundamental reason why -R has to allocate a single block. In all cases we should be checking the same thing - are the addresses we need available on the host? Having different code paths calling guest_validate_base, etc. for different reasons makes me think we're doing it wrong :-) Paul
