ARM Cortex A-53 / 72 errata mitigations #189
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This targeted are Raspberry Pi 3&4 users: There are known faults at the chip level with ARM Cortex A-53, as per the Arm Developer errata notice https://developer.arm.com/documentation/epm048406/2100/ where: 835769: AArch64 multiply-accumulate instruction might produce incorrect result (page 20 of that document) and 843419: A load or store might access an incorrect address (page 22) To mitigate for this gcc has additional build flags: https://gcc.gnu.org/onlinedocs/gcc.pdf (Page 315) -mfix-cortex-a53-835769 -mno-fix-cortex-a53-835769 Enable or disable the workaround for the ARM Cortex-A53 erratum number 835769. This involves inserting a NOP instruction between memory instructions and 64-bit integer multiply-accumulate instructions. -mfix-cortex-a53-843419 -mno-fix-cortex-a53-843419 Enable or disable the workaround for the ARM Cortex-A53 erratum number 843419. This erratum workaround is made at link time and this will only pass the corresponding flag to the linker. Which Monero implemented: monero-project/monero/commit/cf10e05cc6a0ed495dbdd44ec3a76b964b14edba And can be seen working/triggered as during build. Is this applicable through any of the pools verification functions?
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Draft Pull Request as not sure how applicable. |
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I have Raspberry Pi 3b+ and P2Pool runs just fine there. |
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Actually... The mystery is solved now :D tevador/RandomX@457c0e4 |
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I've added these command line flags to build scripts: 8d9b9e5 |
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Glad to see this has been useful, even as an awareness piece for RandomX hardware issues. |
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Applicable to all ARM A-53 single board computers but primarily targeted at Raspberry Pi 3&4 users as those will be the most numerous:
There are known faults at the chip level with ARM Cortex A-53, as per the Arm Developer errata notice developer.arm.com/documentation where:
835769: AArch64 multiply-accumulate instruction might produce incorrect result (page 20 of that document)
and
843419: A load or store might access an incorrect address (page 22)
To mitigate for this gcc has additional build flags:
https://gcc.gnu.org/onlinedocs/gcc.pdf (Page 315)
-mfix-cortex-a53-835769
-mno-fix-cortex-a53-835769
Enable or disable the workaround for the ARM Cortex-A53 erratum number
835769. This involves inserting a NOP instruction between memory instructions
and 64-bit integer multiply-accumulate instructions.
-mfix-cortex-a53-843419
-mno-fix-cortex-a53-843419
Enable or disable the workaround for the ARM Cortex-A53 erratum number
843419. This erratum workaround is made at link time and this will only pass
the corresponding flag to the linker.
Which Monero implemented:
monero-project/monero/commit/cf10e05cc6a0ed495dbdd44ec3a76b964b14edba
And can be seen working/triggered as during build.
Is this applicable through any of the pools verification functions?