Messages in this thread | | | Date | Mon, 17 Dec 2012 13:05:47 +0400 | From | Pavel Emelyanov <> | Subject | Re: [CRIU] [PATCH] Add VDSO time function support for x86 32-bit kernel |
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On 12/14/2012 10:44 PM, Andy Lutomirski wrote: > On Fri, Dec 14, 2012 at 10:35 AM, H. Peter Anvin <hpa@zytor.com> wrote: >> On 12/14/2012 12:34 AM, Pavel Emelyanov wrote: >>> On 12/14/2012 06:20 AM, Andy Lutomirski wrote: >>>> On Thu, Dec 13, 2012 at 6:18 PM, H. Peter Anvin <hpa@zytor.com> wrote: >>>>> Wouldn't the vdso get mapped already and could be mremap()'d. If we >>>> really need more control I'd almost push for a device/filesystem node >>>> that could be mmapped the usual way. >>>> >>>> Hmm. That may work, but it'll still break ABI. I'm not sure that >>>> criu is stable enough yet that we should care. Criu people? >>> >>> It's not yet, but we'd still appreciate the criu-friendly vdso redesign. >>> >>>> (In brief summary: how annoying would it be if the vdso was no longer >>>> just a bunch of constant bytes that lived somewhere?) >>> >>> It depends on what vdso is going to be. In the perfect case it should >>> a) be mremap-able to any address (or be at fixed address _forever_, but >>> I assume this is not feasible); >>> b) have entry points at fixed (or somehow movable) places. >>> >>> I admit that I didn't understand your question properly, if I did, >>> please correct me. >>> >> >> mremap() should work. At the same time, the code itself is not going to >> have any stability guarantees between kernel versions -- it obviously >> cannot. > > We could guarantee that the symbols in the vdso resolve to particular > offsets within the vdso. (Yes, this is ugly.) > > Does criu support checkpointing with one version of a shared library > and restoring with another?
No, neither we have this in plans. However, if somebody needs this and implements -- why not?!
Thanks, Pavel
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