Date: Mon, 23 Aug 2010 08:46:40 -0700 From: Garrett Cooper <gcooper@FreeBSD.org> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-hackers@freebsd.org, hackers@freebsd.org Subject: Re: Question about printcpuinfo in sys/amd64/amd64/indentcpu.c Message-ID: <AANLkTimRTv5sy9TbRN1LgKtgbfzFf0Fkq2MirhdyY3RY@mail.gmail.com> In-Reply-To: <201008230807.59582.jhb@freebsd.org> References: <AANLkTi=CB4eyZPsj%2BNdFfYo3bhQ-P=1icnxAHx3VaT%2Bn@mail.gmail.com> <201008230807.59582.jhb@freebsd.org>
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On Mon, Aug 23, 2010 at 5:07 AM, John Baldwin <jhb@freebsd.org> wrote:
> On Friday, August 20, 2010 10:14:46 am Garrett Cooper wrote:
>> Hi,
>> Currently the code in identcpu.c does a check for a specific cpu
>> value extension. This is set to 0x80000004 (even though the
>> corresponding code below iterates through 0x80000002:0x80000005):
>
> It does not invoke 0x80000005 (<, not <=, is used as the loop terminator).
>
>> /* Check for extended CPUID information and a processor name. */
>> if (cpu_exthigh >= 0x80000004) {
>> brand = cpu_brand;
>> for (i = 0x80000002; i < 0x80000005; i++) {
>> do_cpuid(i, regs);
>> memcpy(brand, regs, sizeof(regs));
>> brand += sizeof(regs);
>> }
>> }
I'm blind :/. I did some poking around and now I know why it's
doing that. It's checking for the items noted in chapter 4.2 Brand
String under the "Intel Processor Identification and the CPUID
Instruction" spec.
Thanks,
-Garrett
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