• Rusty Russell's avatar
    virtio: Force use of power-of-two for descriptor ring sizes · 42b36cc0
    Rusty Russell authored
    The virtio descriptor rings of size N-1 were nicely set up to be
    aligned to an N-byte boundary.  But as Anthony Liguori points out, the
    free-running indices used by virtio require that the sizes be a power
    of 2, otherwise we get problems on wrap (demonstrated with lguest).
    So we replace the clever "2^n-1" scheme with a simple "align to page
    boundary" scheme: this means that all virtio rings take at least two
    pages, but it's safer than guessing cache alignment.
    Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
virtio_ring.h 3.1 KB