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Finally fixed the cc hang for good.

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The problem was that two consequtive reads of the RTC in quick
succession within the compiler was used to validate the
results in the buffer filled by the mtimes syscall.

This syscall buffer is potentially filled by another processor
or by the same one, so the programmers decided to use two
techniques to decide if the results are reliable:
1. Read the buffer twice and compare
2. Make sure that the two reads happened within 200 clock-cycles
   from one another.

Since our RTC is based on the host clock, the actual time
passed between those two instructions depends on the host
speed.

This fix allows for a - programmable - interval within which
if two RTC queries are made, we return an artificially low
delta time. This makes cc happy, while doesn't interfere
with normal OS operation and scheduling.

The setting (RealTimeClockChunkLimit, which defaults to 5000)
might need to be adjusted for slow machines, such as the
RaspberryPi4 or similar.
This commit is contained in:
Andras Tantos
2020-10-02 02:05:40 +00:00
parent 7f4fdc8144
commit 24b615cba1
3 changed files with 29 additions and 6 deletions
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15
simulator/sim_lib/sys_task_req.cpp
View File

@@ -206,12 +206,15 @@ void PrintIntArg(std::ostream &aLogger, size_t aArg, const ExchangePacket_c &aEx
void ParseUnicosExchangePacket(const ExchangePacket_c &aCurrentEP, const ExchangePacket_c &aNewEP, std::ostream &aLogger, const Cpu_c &aCpu) {
static size_t LastSysCall = SIZE_MAX;
const Mainframe_c &Mainframe = aCpu.GetMainframe();
if (aCurrentEP.GetMode().IsMonitorMode()) {
CInt_t S[8];
for (size_t Idx = 0; Idx<sizeof(S) / sizeof(S[0]); ++Idx) S[Idx] = aNewEP.GetS(Idx);
CInt_t A[8];
for (size_t Idx = 0; Idx<sizeof(A) / sizeof(A[0]); ++Idx) A[Idx] = aNewEP.GetA(Idx);
//aLogger << "return from monitor mode with XA: " << HexPrinter(aCpu.GetExchangePacketAddress()) << " " << "IBA: " << HexPrinter(aCurrentEP.GetInstBaseAddr());
// Swapping out from monitor mode - parse it as a reply
if (LastSysCall < SysCallTableSize) {
try {
@@ -260,6 +263,16 @@ void ParseUnicosExchangePacket(const ExchangePacket_c &aCurrentEP, const Exchang
aLogger << " , ";
PrintStringArrayArg(aLogger, 2, aCurrentEP, Mainframe);
break;
case 0x9b: // waitpid
PrintIntArg(aLogger, 0, aCurrentEP, Mainframe);
aLogger << " , ";
PrintPtrArg(aLogger, 1, aCurrentEP, Mainframe);
aLogger << " , ";
PrintIntArg(aLogger, 2, aCurrentEP, Mainframe);
break;
case 125: // mtimes
PrintPtrArg(aLogger, 0, aCurrentEP, Mainframe);
break;
default:
for (uint32_t ArgIdx = 0; ArgIdx < std::min(Entry.ArgCnt, uint32_t(10)); ++ArgIdx) {
if (ArgIdx != 0) aLogger << " , ";
@@ -285,6 +298,8 @@ void ParseUnicosExchangePacket(const ExchangePacket_c &aCurrentEP, const Exchang
//aLogger << "XA: " << HexPrinter(aCpu.GetExchangePacketAddress()) << " " << "IBA: " << HexPrinter(aCurrentEP.GetInstBaseAddr()) << " ";
//aLogger << "unknown SYSCALL with S0 = " << HexPrinter(S[0]);
}
} else {
//aLogger << "entering monitor mode with XA: " << HexPrinter(aCpu.GetExchangePacketAddress()) << " " << "IBA: " << HexPrinter(aCurrentEP.GetInstBaseAddr()) << " ";
}
}
}