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[font=Tahoma,]Linux 3.8ÄÚºËÆäʵ»¹Ã»ÓС°ÕæÕýµÄ¡±CPUÈȲå°ÎÖ§³Ö£¬µ«ÊÇ¿ª·¢ÈËÔ±[/font][font=Tahoma,]ÒѾ­ÔÚ²»¶Ï½Ó½ü¡£½ñÌìÔçÉÏ£¬[/font][font=Tahoma,]Ingo MolnarÌá½»Á˹ØÓÚÔÚLinux 3.8°æ±¾ÖÐÌṩ¶Ôx86´¦ÀíÆ÷ͨÓÃÐÔÖ§³ÖµÄpull request¡£¾¡¹ÜLinuxÄÚºËÒѾ­ÓÐÁ˶ÔCPUÈÈͦ°ÎµÄÖ§³Ö£¬È»¶øµ½Ä¿Ç°ÎªÖ¹£¬[/font][font=Tahoma,]Ê׸ö£¨Æô¶¯£©´¦ÀíÆ÷ÈÔÈ»ÎÞ·¨ÈÈͦ°Î¡£[/font]
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[align=left][font=Tahoma,]תÔØÇë×¢Ã÷£ºLinuxÈËÉçÇø>Ó¢ÎÄ×ÊѶ·­Òëר°æ.±àÒë[/font][/align][font=Tahoma,]Ó¢ÎÄÔ­ÎÄ£º[/font]Linux Works Towards True CPU Hotplug Support
[font=Tahoma,]Posted by Michael Larabel on December 11, 2012[/font]
[font=Tahoma,]One of the first pull requests sent in following the [/font][font=Tahoma,]the Linux 3.7 kernel release is for getting closer to "true CPU hotplug support" with the Linux 3.8 kernel.[/font]
[font=Tahoma,]There isn't yet "true" CPU hotplug support for Linux 3.8, but developers are getting closer. Ingo Molnar[/font][font=Tahoma,] sent in this morning the x86 generic[/font][font=Tahoma,]pull request[/font][font=Tahoma,] for 3.8. While the Linux kernel has had CPU hotplugging support, up to this point you haven't been able to hotplug the first (boot) processor. [/font]
[font=Tahoma,]With this pull for the Linux 3.8 kernel, it will become possible to online/offline the boot processor just like any other x86 CPUs. This feature right now will be supported first by Intel CPUs. For 3.8, this feature is behind a configuration option that is disabled by default. [/font]
[indent]This tree enables CPU#0 (the boot processor) to be onlined/offlined on x86, just like any other CPU. Enabled on Intel CPUs for now.

Allowing this required the identification and fixing of latent CPU#0 assumptions (such as CPU#0 initializations, etc.) in the x86 architecture code, plus the identification of barriers to BSP-offlining, such as active PIC interrupts which can only be serviced on the BSP.

It's behind a default-off option, and there's a debug option that allows the automatic testing of this feature.

The motivation of this feature is to allow and prepare for true CPU-hotplug hardware support: recent changes to MCE support enable us to detect a deteriorating but not yet hard-failing L1/L2 cache on a CPU that could be soft-unplugged - or a failing L3 cache on a multi-socket system.

Note that true hardware hot-plug is not yet fully enabled by this, because that requires a special platform wakeup sequence to be sent to the freshly powered up CPU#0. Future patches for this are planned, once such a platform exists. Chicken and egg[/indent]