diff options
| -rw-r--r-- | src/arch/x86/include/ipxe/cpuid.h | 3 | ||||
| -rw-r--r-- | src/arch/x86/interface/pcbios/rtc_entropy.c | 11 |
2 files changed, 14 insertions, 0 deletions
diff --git a/src/arch/x86/include/ipxe/cpuid.h b/src/arch/x86/include/ipxe/cpuid.h index b5403bd9d..3983dfb89 100644 --- a/src/arch/x86/include/ipxe/cpuid.h +++ b/src/arch/x86/include/ipxe/cpuid.h @@ -42,6 +42,9 @@ struct x86_features { /** Hypervisor is present */ #define CPUID_FEATURES_INTEL_ECX_HYPERVISOR 0x80000000UL +/** TSC is present */ +#define CPUID_FEATURES_INTEL_EDX_TSC 0x00000010UL + /** FXSAVE and FXRSTOR are supported */ #define CPUID_FEATURES_INTEL_EDX_FXSR 0x01000000UL diff --git a/src/arch/x86/interface/pcbios/rtc_entropy.c b/src/arch/x86/interface/pcbios/rtc_entropy.c index e9e6baa59..e0c175685 100644 --- a/src/arch/x86/interface/pcbios/rtc_entropy.c +++ b/src/arch/x86/interface/pcbios/rtc_entropy.c @@ -36,6 +36,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL ); #include <biosint.h> #include <pic8259.h> #include <rtc.h> +#include <ipxe/cpuid.h> #include <ipxe/entropy.h> /** Maximum time to wait for an RTC interrupt, in milliseconds */ @@ -174,8 +175,17 @@ static int rtc_entropy_check ( void ) { * @ret rc Return status code */ static int rtc_entropy_enable ( void ) { + struct x86_features features; int rc; + /* Check that TSC is supported */ + x86_features ( &features ); + if ( ! ( features.intel.edx & CPUID_FEATURES_INTEL_EDX_TSC ) ) { + DBGC ( &rtc_flag, "RTC has no TSC\n" ); + rc = -ENOTSUP; + goto err_no_tsc; + } + /* Hook ISR and enable RTC interrupts */ rtc_hook_isr(); enable_irq ( RTC_IRQ ); @@ -191,6 +201,7 @@ static int rtc_entropy_enable ( void ) { rtc_disable_int(); disable_irq ( RTC_IRQ ); rtc_unhook_isr(); + err_no_tsc: return rc; } |