> Ted Unangst wrote: > > Otto Moerbeek wrote: > > > Sparc64 and powerpc also have speculative execution, branch > > > prediction and extensive caches. It is much wiser to assume they are > > > also affected by (similar) bugs/explots or whatever you call it. > > > > A lot of the commonly available sparc64 gear, T2 and USIII, are in order. > > So that's not exactly right, since branch prediction and speculative exection > are somewhat orthogonal to out of order execution. I'm assuming they are > somewhat less affected because without all the fun out of order machinery the > CPU won't go nearly so far down the branch. > > Specifically regarding meltdown, sparc64 doesn't map the kernel in userland, > right?
sun4u have a split U vs S I/Dtlbs. Those TLB are software-updated. I'm not entirely sure of the sun4v situation. > Regarding spectre, the bounds check bypass requires executing past two > branches. Can a sparc do that? doubt it. Note since the tlb are software-updated if a branch prefetched an unmapped page and that page translation didn't exist, we'd have seen seen spurious speculative faults in the past, because our software-update codepath isn't a willing party to such an emmisions scandal.
