From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [PATCH] [15/105] x86_64: Add documentation for CPU hotplug ACPI extension Date: Mon, 16 Jan 2006 23:08:58 +0100 Message-ID: <200601162308.59433.ak@suse.de> References: Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Disposition: inline Sender: linux-acpi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Brown, Len" Cc: torvalds-3NddpPZAyC0@public.gmane.org, discuss-Wa75r+71Mmgdnm+yROfE0A@public.gmane.org, akpm-3NddpPZAyC0@public.gmane.org, "Raj, Ashok" , linux-acpi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-acpi@vger.kernel.org On Monday 16 January 2006 23:02, Brown, Len wrote: > (corrected Ashok Raj's e-mail address, added linux-acpi). > > One problem here is that big systems will not specify > even all the _present_ CPUs in the MADT -- they'll be > in the DSDT; as the MADT method I s limited to 256. The x86 APICs are limited to 256 CPUs anyways, so I don't see any bigger systems any time soon. Before going to that size x86 Linux will have many other scaling issues fixed anyways - for example you can't have more than 256 interrupt vectors right now and only one per CPU is definitely not enough. There are other issues like this. I would guess the practical limit right now is 64 maybe 128 threads Anyways, DSDT is supported too. We'll use the standard callback which is AFAIK run by the DSDT too. -Andi - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html