On Thu, Mar 13, 2014 at 11:21 AM, H. Peter Anvin <h...@zytor.com> wrote: > On 03/13/2014 11:08 AM, H. Peter Anvin wrote: >> On 03/13/2014 10:28 AM, Andy Lutomirski wrote: >>> >>> Does this mean you prefer the relocation approach to the compat vdso >>> removal approach? It seems like Linus is okay with either one. >>> >> >> Actually, thinking about it, removing it is probably better: >> >> a) gets rid of legacy code, making room for unification; >> b) either way enabling compat support (either relocation or disabling >> the vdso) has a performance penalty for *all* processes. >> >> The only way to avoid that is to have a vdso at a fixed addresses across >> all processes, either in the fixmap or in the user area (presumably at >> the very top.) >> > > So going back and re-reading all the threads, the consensus was to > remove the compat vdso, but recycling the CONFIG_COMPAT_VDSO > configuration option name for the default-disable option. >
I don't recall anyone suggesting keeping the name. CONFIG_COMPAT_VDSO will henceforth be a silly name, since the "compat" mode won't have a vdso. The consensus was that the default should be no vdso, right? My most recent patchset calls it CONFIG_ENABLE_VDSO32_BY_DEFAULT and defaults to n. --Andy > It is important that anyone who actually cares about performance unsets > the option. Should there be a warning at startup if the option is set? --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
