Messages in this thread | | | Date | Tue, 23 Aug 2011 18:58:18 +0200 | From | Richard Weinberger <> | Subject | Re: [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386) |
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Am 23.08.2011 18:53, schrieb Al Viro: > On Tue, Aug 23, 2011 at 09:29:29AM -0700, Linus Torvalds wrote: > >> Oh yes. >> >> System call performance is *important*. And x86 is *important*. >> >> UML? In comparison, not that important. >> >> So quite frankly, if this is purely an UML issue (and unless we're >> missing something else, that's what it looks like, despite all the >> confusion we've had so far), then if we have a choice between "remove >> syscall instruction" and "remove UML", then ... > > Agreed. Note, BTW, that UML has perfectly usable workaround for 99% of > that - don't tell the binaries it has *any* vdso in such cases. And > "remove UML" turns into "remove support under UML for 32bit binaries > that go out of their way to do SYSCALL directly, which wouldn't work > on native 32bit", which is really a no-brainer.
What about this hack/solution? While booting UML can check whether the host's vDSO contains a SYSCALL instruction. If so, UML will not make the host's vDSO available to it's processes...
Thanks, //richard
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