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Kernel: Add RTC as fallback entropy source if HPET is not found

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This commit is contained in:
Maciej Zygmanowski 2021-01-24 12:25:03 +01:00 • committed by Andreas Kling
parent 0a61924727
commit 645657865d
2 changed files with 14 additions and 2 deletions
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14
Kernel/Random.cpp
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@ -30,6 +30,7 @@
#include <Kernel/Devices/RandomDevice.h>
#include <Kernel/Random.h>
#include <Kernel/Time/HPET.h>
#include <Kernel/Time/RTC.h>
#include <Kernel/Time/TimeManagement.h>
namespace Kernel {
@ -65,14 +66,23 @@ KernelRng::KernelRng()
this->resource().add_random_event(value, i % 32);
}
} else {
} else if (TimeManagement::the().can_query_precise_time()) {
// Add HPET as entropy source if we don't have anything better.
klog() << "KernelRng: Using HPET as entropy source (bad!)";
klog() << "KernelRng: Using HPET as entropy source";
for (size_t i = 0; i < resource().pool_count * resource().reseed_threshold; ++i) {
u64 hpet_time = HPET::the().read_main_counter();
this->resource().add_random_event(hpet_time, i % 32);
}
} else {
// Fallback to RTC
klog() << "KernelRng: Using RTC as entropy source (bad!)";
time_t current_time = RTC::now();
for (size_t i = 0; i < resource().pool_count * resource().reseed_threshold; ++i) {
this->resource().add_random_event(current_time, i % 32);
current_time *= 0x574a;
current_time += 0x40b2;
}
}
}