Broddo
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Re: NIOSV/g with FPU: inconsistent calculation results
@BoonBengT_Altera @LYGOOI My apologies again for the delay in responding. Yes I can confirm that the work-around suggested by @LYGOOI does address the problem - the FPU is producing consistently correct results now, so thanks for this! However, disabling caching is a big trade off for my project as I'm executing in place from external flash. I'll need to profile this to determine if FPU without cache is more performant than soft-float with cache. For now, I'm working with the latter and will wait for the fix in a coming release. Thanks once again, BroddoRe: NIOSV/g with FPU: inconsistent calculation results
Thanks for the reply @LYGOOI and apologies for the delay in getting back to you - I was on vacation. To answer your questions: I'm using Quartus Lite 24.1 and I've pasted the CPU parameters below. I've attached the test project that builds all of this. I'm running on a custom board (that was previously running a NIOS2 application with no issues). If you want to run it yourself, the only change you'll have to make is the location of the source clock. For convenience, I've added a Makefile that will build the project and the software - you'll see for yourself. Here are the CPU parameters <module name="intel_niosv_g_0" kind="intel_niosv_g" version="4.0.0" enabled="1"> <parameter name="AUTO_CLK_CLOCK_DOMAIN" value="3" /> <parameter name="AUTO_CLK_RESET_DOMAIN" value="3" /> <parameter name="AUTO_DEVICE" value="10M50DAF484C8G" /> <parameter name="AUTO_DEVICE_SPEEDGRADE" value="8" /> <parameter name="Blind_Window_Period" value="1000" /> <parameter name="CLICenabledInterruptMode" value="0" /> <parameter name="CLICenabledShadowRegisterFiles" value="1" /> <parameter name="CUSTOM_OP" value="" /> <parameter name="Default_Timeout_Period" value="255" /> <parameter name="SUB_OP" value="" /> <parameter name="alignCLICVectorTable" value="8" /> <parameter name="basicInterruptMode" value="0" /> <parameter name="basicShadowRegisterFiles" value="0" /> <parameter name="clockFrequency" value="75000000" /> <parameter name="dataCacheSize" value="4096" /> <parameter name="dataSlaveMapParam"><![CDATA[<address-map><slave name='onchip_flash.data' start='0x0' end='0x160000' type='altera_onchip_flash.data' /><slave name='onchip_memory.s1' start='0x200000' end='0x214000' type='altera_avalon_onchip_memory2.s1' /><slave name='intel_niosv_g_0.dm_agent' start='0x220000' end='0x230000' type='intel_niosv_g.dm_agent' /><slave name='intel_niosv_g_0.timer_sw_agent' start='0x230000' end='0x230040' type='intel_niosv_g.timer_sw_agent' /><slave name='jtag_uart_0.avalon_jtag_slave' start='0x230040' end='0x230048' type='altera_avalon_jtag_uart.avalon_jtag_slave' /><slave name='onchip_flash.csr' start='0x230048' end='0x230050' type='altera_onchip_flash.csr' /></address-map>]]></parameter> <parameter name="deviceFamily" value="MAX 10" /> <parameter name="disableFsqrtFdiv" value="false" /> <parameter name="dtcm1Base" value="18874368" /> <parameter name="dtcm1InitFile" value="" /> <parameter name="dtcm1Size" value="0" /> <parameter name="dtcm2Base" value="0" /> <parameter name="dtcm2InitFile" value="" /> <parameter name="dtcm2Size" value="0" /> <parameter name="enableBranchPrediction" value="true" /> <parameter name="enableCLICInterruptEdgeTriggerConfig" value="false" /> <parameter name="enableCLICInterruptPolarityConfig" value="false" /> <parameter name="enableCLICSelectiveHardwareVectoring" value="false" /> <parameter name="enableCoreLevelInterruptController" value="false" /> <parameter name="enableDebug" value="true" /> <parameter name="enableDebugReset" value="true" /> <parameter name="enableECCFull" value="false" /> <parameter name="enableECCLite" value="false" /> <parameter name="enableFPU" value="true" /> <parameter name="enableLockstep" value="false" /> <parameter name="enableLockstepExtRst" value="false" /> <parameter name="enableMulDiv" value="true" /> <parameter name="funct3" value="" /> <parameter name="funct7_l" value="" /> <parameter name="funct7_u" value="" /> <parameter name="hartId" value="0" /> <parameter name="instCacheSize" value="4096" /> <parameter name="instSlaveMapParam"><![CDATA[<address-map><slave name='onchip_flash.data' start='0x0' end='0x160000' type='altera_onchip_flash.data' /><slave name='onchip_memory.s1' start='0x200000' end='0x214000' type='altera_avalon_onchip_memory2.s1' /><slave name='intel_niosv_g_0.dm_agent' start='0x220000' end='0x230000' type='intel_niosv_g.dm_agent' /></address-map>]]></parameter> <parameter name="itcm1Base" value="19922944" /> <parameter name="itcm1InitFile" value="" /> <parameter name="itcm1Size" value="0" /> <parameter name="itcm2Base" value="0" /> <parameter name="itcm2InitFile" value="" /> <parameter name="itcm2Size" value="0" /> <parameter name="mnemonic" value="" /> <parameter name="numCLICDebugTriggers" value="0" /> <parameter name="numCLICLevels" value="2" /> <parameter name="numCLICPlatformInterrupts" value="16" /> <parameter name="numCLICPriorities" value="8" /> <parameter name="opcode" value="" /> <parameter name="peripheralRegionABase" value="2293760" /> <parameter name="peripheralRegionASize" value="65536" /> <parameter name="peripheralRegionBBase" value="67108864" /> <parameter name="peripheralRegionBSize" value="2097152" /> <parameter name="resetOffset" value="0" /> <parameter name="resetSlave" value="onchip_flash.data" /> <parameter name="useResetReq" value="false" /> </module>NIOSV/g with FPU: inconsistent calculation results
I'm using a NIOSV/g with FPU enabled in a MAX10 project. The project involves heavy use of float point calculations, hence the need for the FPU. I noticed some occasionally inconsistent results in this program and started debugging - assuming this was a bug in my code. However I was able to run my code in a simulator and on a different RISCV microcontroller and everything worked flawlessly. I also disabled the FPU in the NIOSV design and again the code ran fine. In order to recreate the problem, I created a basic project with just the NIOSV, some RAM and the JTAG-Uart. I also wrote a tiny C program to stress test the FPU. The results of this show that again, the FPU is producing incorrect results. I've attached a screenshot of the Platform Designer design. I'm running the design at 75Mhz and the design meets timing requirements. Here is the code I ran. Note that I have interrupts disabled to be sure this isn't a context switching issue. I also did not wrap the calculations into a function so I could more easily view the various calculation results in the debugger. This code works as expected when using a soft-FPU. When using the NIOSV FPU, results are inconsistent. I've attached a screenshot of one failed cycled. You can see that a1 and b1 are not equal. #include <stdint.h> #include <math.h> #include "sys/alt_stdio.h" static void fpuTest(void) { int fail_count = 0; int iteration = 0; while (1) { float a0 = (float)iteration * 0.001f; float a1 = 1.1f * sinf((float)iteration * 0.1f); float a2 = 2.2f / (1.0f + (float)iteration * 0.0001f); float a3 = sqrtf(3.3f + (float)iteration); float a4 = powf(4.4f + (float)iteration, 1.1f); float a5 = logf(5.5f + (float)iteration + 1.0f); float a6 = 6.6f * cosf((float)iteration * 0.05f); float a7 = 7.7f + tanf((float)iteration * 0.02f); float result_a = a0 + a1 + a2 + a3 + a4 + a5 + a6 + a7; float b0 = (float)iteration * 0.001f; float b1 = 1.1f * sinf((float)iteration * 0.1f); float b2 = 2.2f / (1.0f + (float)iteration * 0.0001f); float b3 = sqrtf(3.3f + (float)iteration); float b4 = powf(4.4f + (float)iteration, 1.1f); float b5 = logf(5.5f + (float)iteration + 1.0f); float b6 = 6.6f * cosf((float)iteration * 0.05f); float b7 = 7.7f + tanf((float)iteration * 0.02f); float result_b = b0 + b1 + b2 + b3 + b4 + b5 + b6 + b7; // Check if result is consistent (should be identical) if (fabsf(result_a - result_b) > 1e-6f) { alt_printf("FPU test failed at iteration %x\n", iteration); fail_count++; } iteration++; } } int main(void) { // Make sure interrupts are disabled __asm volatile ( "csrc mstatus, 8" ); fpuTest(); while (1); return 0; } Can someone help me investigate what could be wrong here? Could there be an issue in the FPU itself?Re: Nois V Command Shell Error
I've run afoul of this as well. There seems to be a discrepancy between the command-line arguments referenced in the docs, the commands that niosv-bsp claims to support and actually available in niosv-bsp. The solution for now: try leaving out the --quartus-project switch. It's not necessary niosv-bsp -c -s=sys_module.sopcinfo -t=hal sw/bsp_custom/settings.bsp
