Re: [Xen-devel] [PATCH v2 1/5] x86/entry: Correct comparisons against boolean variables

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 27.02.18 at 15:50, <andrew.cooper3@xxxxxxxxxx> wrote:
> The correct way to check a boolean is `cmpb $0` or `testb $0xff`, whereas a
> lot of our entry code uses `testb $1`.  This will work in principle for values
> which are really C _Bool types, but won't work for other integer types which
> are intended to have boolean properties.
> 
> cmp is the more logical way of thinking about the operation, so adjust all
> outstanding uses of `testb $1` against boolean values.  Changing test to cmp
> changes the logical mnemonic of the following condition from 'zero' to
> 'equal', but the actual encoding remains the same.
> 
> No functional change, as all uses are real C _Bool types, and confirmed by
> diffing the disassembly.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Thanks, one less item on the list of things I keep forgetting to
actually do.

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

Jan


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