On 03/19/2015 12:26 AM, Andy Lutomirski wrote: > On Wed, Mar 18, 2015 at 1:02 PM, Oleg Nesterov <[email protected]> wrote: >> On 03/18, Andrey Wagin wrote: >>> >>> This patch fixes the problem. Oleg, could you send this path in the >>> criu maillist? >> >> Sure, will do. > > We still haven't answered one question: what's the kernel's position > on ABI stability wrt CRIU? We clearly shouldn't make changes that > break the principle of CRIU, but CRIU encodes so many tricky > assumptions about the inner workings of the kernel that it's really > tough to avoid breaking old CRIU versions.
Well, we try hard to use only documented kernel API-s. Isn't the sigframe considered to be some sort of "stable API"? I mean -- it's visible by the userspace, nobody prevents glibc or gdb from messing with this stuff just by reading it from memory. If it's "parse-able" e.g. like VDSO is, but we don't do it in CRIU -- then it's definitely a CRIU BUG to be fixed. > So... do we introduce somewhat nasty code into the kernel to keep old > CRIU versions working, or do we require that users who want to restore > onto new kernels use new CRIU? It's OK (I think) to require newer versions of CRIU, it's easy to update one unlike the kernel ;) But if "old" version of CRIU just crash the restored processes on "new" kernels and there's no way to detect this properly -- that's the problem. > (It seems clear to me that CRIU should apply the patch regardless of > what the kernel does. It will enable CRIU to work on the same class > of programs that are fixed by the kernel change that started this > thread.) > > --Andy > . > Thanks, Pavel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
