Date: Fri, 31 Jan 2003 17:17:54 -0500 (EST) From: John Baldwin <jhb@FreeBSD.org> To: Julian Elischer <julian@elischer.org> Cc: "Daniel C. Sobral" <dcs@tcoip.com.br>, freebsd-current@FreeBSD.ORG, Trish Lynch <trish@bsdunix.net>, Matthew Dillon <dillon@apollo.backplane.com> Subject: Re: Hyperthreading and machdep.cpu_idle_hlt Message-ID: <XFMail.20030131171754.jhb@FreeBSD.org> In-Reply-To: <Pine.BSF.4.21.0301311323310.45015-100000@InterJet.elischer.org>
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On 31-Jan-2003 Julian Elischer wrote: > > > On Fri, 31 Jan 2003, John Baldwin wrote: > >> >> On 31-Jan-2003 Julian Elischer wrote: >> > >> > >> > On Fri, 31 Jan 2003, John Baldwin wrote: >> > >> >> >> AT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,<b28>,ACC> >> >> >> >> >> >> It has HTT set but it's only a 1.2GHz box and I heard somewhere that only >> >> >> 2+ GHz P4's had hyperthreading. I noticed some MFCs to stable that >> >> >> suggested hyperthreading support but I do not know if full hyperthreading >> >> >> support has been MFCd yet or is intended to be MFCd to -stable. >> >> > >> >> > AFAIK, full hyperthreading support, as it is, has been merged to >> >> > -stable. It consists of a patch to recognize the virtual CPUs, so they >> >> > will be dealt with like any SMP system, as long as HTT is enabled on the >> >> > BIOS. >> >> >> >> Well, sort of. We have no way of knowing if it is off in the BIOS unless >> >> we use the ACPI tables to enumerate CPU's (which we don't), so turning it >> >> off in the BIOS won't turn it off in FreeBSD for the time being. :) >> >> >> > I have a 2,8GHz p4 here which has HTT and has a bios option for >> > >> > Interrupt mode: [APIC/PIC] >> > >> > I'm using APIC mode but an SMP (today's 4.x) kernel >> > panics imediatly saying it can;t find an APIC. >> >> You need to have an mptable for it to work. The mptable will >> only list one processor, but it still needs to be there. > > if that comes from the BIOS, can it be simulated for > uniprocessor machines with HTT? No. It provides information on how to route PCI interrupts through the IO APIC. ACPI also has this information, but we don't handle the IO APIC case right in ACPI yet. That is on my todo list but is a much larger task and will not be a 4.x feature. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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