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Date: Mon, 24 Mar 2014 15:52:06 -0400
From: Neil Horman <nhorman@tuxdriver.com>
To: "H. Peter Anvin" <hpa@linux.intel.com>
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Subject: Re: [dpdk-dev] [PATCH v3] eal_common_cpuflags: Fix %rbx corruption,
 and simplify the code
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On Mon, Mar 24, 2014 at 11:09:52AM -0700, H. Peter Anvin wrote:
> On 03/24/2014 10:44 AM, Neil Horman wrote:
> > * Modified cpuid_reg enum to start at 1 rather than zero
> > * Added CPUID_REG macro to drop enum value by 1 during access
> 
> I guess I don't get it... why?
> 
To add an extra sanity check in rte_get_flag_enabled.  If we were moving to the
use of C99 initalizers, I wanted something to catch the possibility that we skip
a flag by accident (i.e. leave a zero initalized hole in the array).  Except 0
from my read is a valid value for all the fields of the array.  So I bumped up
the cpuid register enum by one and wrapped it in a macro.  That way we can test
for !feat->reg as an indicator that we're requesting feature support for a flag
thats not listed in the array.
Neil

> 	-hpa
> 
>