AArch64 support for ACPI BERT in Linux

ACPI is not only in the firmware of Intel-based systems, but it’s also now inside ARM-based systems. Today on the Linaro-ACPI mailing list, there was a patch for ACPI BERT support for AArch64. I think support had already been in for Intel already, unclear how long.

APEI Boot Error Record Table (BERT) support

Under normal circumstances, when a hardware error occurs, kernel will be notified via NMI, MCE or some other method, then kernel will process the error condition, report it, and recover it if possible. But sometime, the situation is so bad, so that firmware may choose to reset directly without notifying Linux kernel. Linux kernel can use the Boot Error Record Table (BERT) to get the un-notified hardware errors that occurred in a previous boot. In this patch, the error information is reported via printk. Once error log is printed out clear error status so it would not be print during next boot again.

ACPI/APEI is designed to verifiy/report H/W errors, like Corrected Error(CE) and Uncorrected Error(UC). It contains four tables: HEST, ERST, EINJ and BERT. The first three tables have been merged for a long time, but because of lacking BIOS support for BERT, the support for BERT is pending until now. Recently on ARM 64 platform it is has been supported. So here we come. The following log is a BERT record after system reboot because of hitting a fatal error.

BERT: Obtained BERT iomem region <00000000fe801000-00000000fe802000> for BERT.
[Hardware Error]: Error record from previous boot:
[Hardware Error]: event severity: fatal
[Hardware Error]:  Error 0, type: fatal
[Hardware Error]:   section_type: memory error
[Hardware Error]:   physical_address: 0x00000000fe800000
[Hardware Error]:   physical_address_mask: 0x0000000000000fff
[Hardware Error]:   card: 0 module: 1 bank: 0 device: 1 row: 1 column: 1 bit_pos

For more information about BERT, please refer to ACPI Specification version 6.0, section 18.3.1.

For more information about this patch, see this thread:

For more on BERT, also see /src/acpi/bert/bert.c in the FirmWareTestSuite (FWTS).

Click to access ACPI_6.0.pdf


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