Ingo Molnar wrote: > * travis@sgi.com wrote: > >> This patchset provides the following: >> >> * Generic: Percpu infrastructure to rebase the per cpu area to zero >> >> This provides for the capability of accessing the percpu variables >> using a local register instead of having to go through a table >> on node 0 to find the cpu-specific offsets. It also would allow >> atomic operations on percpu variables to reduce required locking. >> >> * x86_64: Fold pda into per cpu area >> >> Declare the pda as a per cpu variable. This will move the pda >> area to an address accessible by the x86_64 per cpu macros. >> Subtraction of __per_cpu_start will make the offset based from >> the beginning of the per cpu area. Since %gs is pointing to the >> pda, it will then also point to the per cpu variables and can be >> accessed thusly: >> >> %gs:[&per_cpu_xxxx - __per_cpu_start] >> >> * x86_64: Rebase per cpu variables to zero >> >> Take advantage of the zero-based per cpu area provided above. Then >> we can directly use the x86_32 percpu operations. x86_32 offsets >> %fs by __per_cpu_start. x86_64 has %gs pointing directly to the >> pda and the per cpu area thereby allowing access to the pda with >> the x86_64 pda operations and access to the per cpu variables >> using x86_32 percpu operations. > > tried it on x86.git and 1/3 did not build and 2/3 causes a boot hang > with the attached .config. > > Ingo > The build error was fixed with the note I sent to you yesterday with a "fixup" patch for changes in -mm but not in x86.git (attached). I'll try out your config next. Thanks, Mike