Messages in this thread | | | Subject | Re: [PATCH v2 1/4] x86/hyper-v: move synic/stimer control structures definitions to hyperv-tlfs.h | From | Nadav Amit <> | Date | Wed, 28 Nov 2018 09:55:37 -0800 |
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> On Nov 28, 2018, at 5:07 AM, Thomas Gleixner <tglx@linutronix.de> wrote: > > On Wed, 28 Nov 2018, Vitaly Kuznetsov wrote: > >> Nadav Amit <nadav.amit@gmail.com> writes: >> >>> On a different note: how come all of the hyper-v structs are not marked >>> with the “packed" attribute? >> >> "packed" should not be needed with proper padding; I vaguely remember >> someone (from x86@?) arguing _against_ "packed". > > Packed needs to be used, when describing fixed format data structures in > hardware or other ABIs, so the compiler cannot put alignment holes into > them. > > Using packed for generic data structures might result in suboptimal layouts > and prevents layout randomization.
Right, I forgot about the structs randomization. So at least for it, the attribute should be needed.
To prevent conflicts, I think that this series should also add the attribute in a first patch, which would be tagged for stable.
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