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.Dd March 18, 2024
.Dt APEI 4
.Os
.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.Sh NAME
.Nm apei
.Nd ACPI Platform Error Interfaces
.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.Sh SYNOPSIS
.Cd "apei* at apeibus?"
.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.Sh DESCRIPTION
.Nm
reports hardware errors discovered through
.Tn APEI ,
the
.Tn ACPI
Platform Error Interfaces.
.Pp
.Nm
also supports injecting errors.
.\" .Nm
.\" also supports reading/writing/clearing error records in a persistent
.\" firmware store (XXX not yet: nothing uses the ERST).
.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.Sh DIAGNOSTICS
When the hardware detects an error and reports it to
.Nm ,
it will print information about the error to the console.
.Pp
Example of a correctable memory error, automatically corrected by the
system, with no further intervention needed:
.Bd -literal
apei0: error source 1 reported hardware error: severity=corrected nentries=1 status=0x12<CE,GEDE_COUNT=0x1>
apei0: error source 1 entry 0: SectionType={0xa5bc1114,0x6f64,0x4ede,0xb8b8,{0x3e,0x83,0xed,0x7c,0x83,0xb1}} (memory error)
apei0: error source 1 entry 0: ErrorSeverity=2 (corrected)
apei0: error source 1 entry 0: Revision=0x201
apei0: error source 1 entry 0: Flags=0x1<PRIMARY>
apei0: error source 1 entry 0: FruText=CorrectedErr
apei0: error source 1 entry 0: MemoryErrorType=8 (PARITY_ERROR)
.Pp
Example of a fatal uncorrectable memory error:
.Bd -literal
apei0: error source 0 reported hardware error: severity=fatal nentries=1 status=0x11<UE,GEDE_COUNT=0x1>
apei0: error source 0 entry 0: SectionType={0xa5bc1114,0x6f64,0x4ede,0xb8b8,{0x3e,0x83,0xed,0x7c,0x83,0xb1}} (memory error)
apei0: error source 0 entry 0: ErrorSeverity=1 (fatal)
apei0: error source 0 entry 0: Revision=0x201
apei0: error source 0 entry 0: Flags=0x1<PRIMARY>
apei0: error source 0 entry 0: FruText=UncorrectedErr
apei0: error source 0 entry 0: ErrorStatus=0x400<ErrorType=0x4=ERR_MEM>
apei0: error source 0 entry 0: Node=0x0
apei0: error source 0 entry 0: Module=0x0
apei0: error source 0 entry 0: Device=0x0
panic: fatal hardware error
.Ed
.Pp
Details of the hardware error sources can be dumped with
.Xr acpidump 8 .
.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.Sh SEE ALSO
.Xr acpi 4 ,
.Xr acpihed 4 ,
.Xr acpidump 8
.Rs
.%B ACPI Specification 6.5
.%O Chapter 18: ACPI Platform Error Interfaces (APEI)
.%U https://uefi.org/specs/ACPI/6.5/18_Platform_Error_Interfaces.html
.Re
.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.Sh HISTORY
The
.Nm
driver first appeared in
.Nx 11.0 .
.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.Sh AUTHORS
The
.Nm
driver was written by
.An Taylor R Campbell Aq Mt riastradh@NetBSD.org .
.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.Sh BUGS
No sysctl interface to read BERT after boot.
.Pp
No simple sysctl interface to inject errors with EINJ, or any way to
inject errors at physical addresses in pages allocated for testing.
Perhaps there should be a separate kernel module for that.
.Pp
Nothing reads, writes, or clears ERST.
.Nx
could use it to store dmesg or other diagnostic information on panic.
.Pp
Many hardware error source types in the HEST are missing, such as
.Tn PCIe
errors.
.Pp
.Nm
is not wired to any machine-dependent machine check exception
notifications.
.Pp
No formal log format or sysctl/device interface that programs can
reliably act on.
.Pp
.Nx
makes no attempt to recover from uncorrectable but recoverable errors,
such as discarding a clean cached page where an uncorrectable memory
error has occurred.