On 11/04/2014 11:45 AM, tip-bot for Jan Beulich wrote: > Commit-ID: 97b67ae559947f1e208439a1bf6a734da3087006 > Gitweb: http://git.kernel.org/tip/97b67ae559947f1e208439a1bf6a734da3087006 > Author: Jan Beulich <JBeulich@xxxxxxxx> > AuthorDate: Tue, 4 Nov 2014 08:50:48 +0000 > Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > CommitDate: Tue, 4 Nov 2014 20:43:14 +0100 > > x86-64: Use RIP-relative addressing for most per-CPU accesses > > Observing that per-CPU data (in the SMP case) is reachable by > exploiting 64-bit address wraparound (building on the default kernel > load address being at 16Mb), the one byte shorter RIP-relative > addressing form can be used for most per-CPU accesses. The one > exception are the "stable" reads, where the use of the "P" operand > modifier prevents the compiler from using RIP-relative addressing, but > is unavoidable due to the use of the "p" constraint (side note: with > gcc 4.9.x the intended effect of this isn't being achieved anymore, > see gcc bug 63637). > > With the dependency on the minimum kernel load address, arbitrarily > low values for CONFIG_PHYSICAL_START are now no longer possible. A > link time assertion is being added, directing to the need to increase > that value when it triggers. > This description makes very little sense. What matters here is the virtual address, which is always >= -2 GB. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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