Re: [Qemu-devel] Re: [PATCH][v2] Align file accesses with cache=off (O_DIRECT)

[Jamie Lokier]

Anthony Liguori wrote:
> Actually, this is precisely what I'd like to do.  The key is to 
> mmap(MAP_PRIVATE) from the underling file directly into the guest's 
> memory.  Should be just as applicable to QEMU as KVM (although for KVM 
> we need mmu-notifiers first).

With QEMU, that would lead to a huge number of VMAs - different mmap
address regions.  Linux (or any host for all I know) doesn't handle
that well.

On Linux you could use remap_file_pages to avoid the VMA problem.

-- Jamie