From 0d35411f88dd37dda755d52b4549337f8299c698 Mon Sep 17 00:00:00 2001 From: Michael Brown Date: Tue, 20 Mar 2018 20:42:39 +0200 Subject: [rng] Use fixed-point calculations for min-entropy quantities We currently perform various min-entropy calculations using build-time floating-point arithmetic. No floating-point code ends up in the final binary, since the results are eventually converted to integers and asserted to be compile-time constants. Though this mechanism is undoubtedly cute, it inhibits us from using "-mno-sse" to prevent the use of SSE registers by the compiler. Fix by using fixed-point arithmetic instead. Signed-off-by: Michael Brown --- src/arch/x86/include/ipxe/rtc_entropy.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'src/arch') diff --git a/src/arch/x86/include/ipxe/rtc_entropy.h b/src/arch/x86/include/ipxe/rtc_entropy.h index e214745d..581abcd3 100644 --- a/src/arch/x86/include/ipxe/rtc_entropy.h +++ b/src/arch/x86/include/ipxe/rtc_entropy.h @@ -22,7 +22,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL ); * * @ret min_entropy min-entropy of each sample */ -static inline __always_inline double +static inline __always_inline min_entropy_t ENTROPY_INLINE ( rtc, min_entropy_per_sample ) ( void ) { /* The min-entropy has been measured on several platforms @@ -38,7 +38,7 @@ ENTROPY_INLINE ( rtc, min_entropy_per_sample ) ( void ) { * safety margin to allow for some potential non-independence * of samples. */ - return 1.3; + return MIN_ENTROPY ( 1.3 ); } extern uint8_t rtc_sample ( void ); -- cgit v1.2.3-55-g7522