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ACPI/APEI BERT support for Linux

Tony Luck of Intel submitted a patch to the Linux (Kernel,ACPI) lists, to add ACPI BERT (Boot Error Record Table) support to the Linux kernel. The original patch appears to be from Huang Ying of Intel, I think.

New Linux kernel parameter:
bert_disable: Disable BERT OS support on buggy BIOSes.

Excerpting comments from the patch:

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. 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. For more information about BERT, please refer to ACPI Specification version 6.0, section 18.3.1:
http://www.uefi.org/sites/default/files/resources/ACPI_6.0.pdf

The following log is a BERT record after system reboot because of hitting a fatal memory error:
BERT: Error records from previous boot:
[Hardware Error]: It has been corrected by h/w and requires no further action
[Hardware Error]: event severity: corrected
[Hardware Error]:  Error 0, type: recoverable
[Hardware Error]:   section_type: memory error
[Hardware Error]:   error_status: 0x0000000000000400
[Hardware Error]:   physical_address: 0xffffffffffffffff
[Hardware Error]:   card: 1 module: 2 bank: 3 row: 1 column: 2 bit_position: 5
[Hardware Error]:   error_type: 2, single-bit ECC

For more information, see the patch message thread on the Linux-kernel list:
http://vger.kernel.org/majordomo-info.html

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