Date: Sat, 18 Mar 2006 01:01:22 -0700 From: Scott Long <scottl@samsco.org> To: "Jeremy C. Reed" <reed@reedmedia.net> Cc: freebsd-amd64@freebsd.org Subject: Re: amd64 webpage, 12GB memory? 64-bit or not? SMP or not? Message-ID: <441BBE52.8000204@samsco.org> In-Reply-To: <Pine.NEB.4.62.0603172125420.10693@pilchuck.reedmedia.net> References: <Pine.NEB.4.62.0603171958350.10693@pilchuck.reedmedia.net> <20060318044110.GA8986@troutmask.apl.washington.edu> <Pine.NEB.4.62.0603172125420.10693@pilchuck.reedmedia.net>
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Jeremy C. Reed wrote: > On Fri, 17 Mar 2006, Steve Kargl wrote: > > >>>How can I tell if a 2.80Ghz Xeon is a 32-bit Xeon or a 64-bit Xeon? What >>>do I look for in the 6.0-RELEASE GENERIC i386 dmesg output? I do see: >>> >>>ACPI APIC Table: <PTLTD APIC > >>>Timecounter "i8254" frequency 1193182 Hz quality 0 >>>CPU: Intel(R) Xeon(TM) CPU 2.80GHz (2793.01-MHz 686-class CPU) >> >> ^^^^^^^^^^^^^ >>You're running a i386 kernel, which is 32-bit. > > > I already know what it is currently running. In my email, I tried to > indicate that it is running 6.0-RELEASE GENERIC i386 (twice in the parts > you included in your reply). > > I am unclear if you are answering my question: How can I tell if a 2.80Ghz > Xeon is a 32-bit Xeon or a 64-bit Xeon? > The 'LM' string in the AMD Features lines tells you that it can go into long mode, which means that it can operate in 64 bit mode. > >>>Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,C >>>MOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE> >>> Features2=0x641d<SSE3,RSVD2,MON,DS_CPL,CNTX-ID,CX16,<b14>> >>> AMD Features=0x20100000<NX,LM> >>> Hyperthreading: 2 logical CPUs >>>real memory = 3489071104 (3327 MB) >>>avail memory = 3414630400 (3256 MB) >>> >>>How can I tell if it can take advantage of "options SMP" (from looking at >>>6.0-RELEASE i386 GENERIC output)? (I do see "Hyperthreading: 2 logical >>>CPUs".) >> >>You're using a GENERIC kernel. IIRC, "options SMP" isn't included >>in GENERIC, so you're running a UP kernel. You need to rebuild >>the kernel > > > I understand. I know it is running GENERIC as I mentioned. My question is: > How can I tell if it can take advantage of "options SMP" (from looking at > 6.0-RELEASE i386 GENERIC output)? > How can I tell if my car takes diesel or unleaded? I'm sorry, but this questioning sounds a bit hysterical. But, if you truly have no other way of knowing, compile and run the tool in /usr/src/tools/tools/ncpus. > >>>I was told it has 12 GB of memory. The Hardware Notes also says "The >>>largest tested memory configuration to date is 8GB." But I only see "real >>>memory = 3489071104 (3327 MB)". >> >>The i386 is limited to 4 GB address space without options PAE. You >>need to rebuild your kernel. > > > Only i386 supports "options PAE". How can I tell if this system can > support an amd64 (without physical access)? See above. > > I am still unsure. Sorry if I misunderstood your reply. I know I am > currently running a 6.0-RELEASE i386 GENERIC kernel. (And I know SMP is > not in GENERIC). I want to know how I can find out if I should be running > an amd64 kernel instead. > > I was under the impression that some (all?) 64 bit Athlons, Opterons, > Xeons can also run the 32-bit i386 kernel. (I was sure I have seen this > too.) > > I have been looking at src/sys/i386/i386/identcpu.c. But I am not sure how > an 64-bit Intel Xeon would behave. (I am guessing it would be > CPUCLASS_686.) CPUCLASS_686 refers to Pentium Pro and above CPUs, and significantly predates the 64-bit x86 architecture. But fwiw, the i386 sources files are not a good place to find 64-bit code. > > I do see that my dmesg output has AMD featuress with "LM" which means > 64-bit long mode. But I don't know if that means this is a 64-bit system. YES! > > I see the dmesg says "Id = 0xf43" (this is the cpu_id). Doing some google > searches show one "K8-class" and several "686-class" CPUs. Also NYCBUG's > dmesg database has that same "K8-class" "Id = 0xf43" system. A "K8-class" > is definitely from an amd64 kernel (as it is printed from the > src/sys/amd64/amd64/identcpu.c). > > I am hoping the system I am looking at can run the amd64 kernel. Yes, it sure can. Scott
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