On 8/30/05, Luck, Tony <[EMAIL PROTECTED]> wrote: > At first glance it looks like ia64 should not be treating the UP > case differently from the SMP case. UP kernels place the per-cpu > data up in the top 64K (PERCPU_PAGE_SIZE) of the virtual address > space mapped by DTR[1], just like SMP kernels do ...
That's true. > so all the > space allocation, mapping, and relocation code should be the same > for UP and SMP ... shouldn't they? No, in the UP case, we can simply map the per-CPU section in the kernel image whereas in the SMP case, each CPU needs its own copy of the per-CPU section. To see this, look for per_cpu_init(): in the SMP case, it copies the section, in the UP-case, it simply returns __phys_per_cpu_start (a pointer into the per-CPU section). --david -- Mosberger Consulting LLC, voice/fax: 510-744-9372, http://www.mosberger-consulting.com/ 35706 Runckel Lane, Fremont, CA 94536 - 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
