On Fri, 21 Jan 2005 15:22:18 -0800, "Chen, Kenneth W" <[EMAIL PROTECTED]> wrote: >__gp is positioned so far out that it is almost at the end of all data >sections. On 2.6.11-rc1, 80% of kernel data symbols are out of 22-bit >immediate offset from __gp. This means accessing these symbols are >unnecessarily expansive such that they have to go through global offset >table (a memory load to get the symbol address). Among these out of >reach symbols from __gp, some are very frequently used, like Jiffies, >etc. > >Can we position the __gp somewhat more optimally, to cover more of these >symbols? Something like the following patch would make all of them fall >into the 22-bit immediate offset relative to gp.
The best place for __gp is in the exact middle of the range .data.init_task through the end of .sbss. Unfortunately a large .data section could result in .got and .sbss being out of range of a median __gp. Is it possible in the linker script to first try (.sbss.end - .data.init_task) / 2, then test the result for reachability to .sbss and adjust __gp if necessary? - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
