[Xen-devel] ask a question about ERST

[Zhenzhong Duan <zhenzhong.duan@xxxxxxxxxx>]

Hi maintainer,
I found below patch reverted part of erst header size check.
This lead to mismatch with kernel upstream code and erst disabled on
some machine like X4170 M3/X3-2.
According to the ACPI spec 4.0 and 5.0, the Serialization Header Length
should be the length of Serialization Header.
After revert below patch, xen succeed with erst table init.
So could this patch be reverted now to match acpi spec and kernel upstream?

[root@zhenzhong2 xen-unstable.hg]# hg export 23760
# HG changeset patch
# User Keir Fraser <keir@xxxxxxx>
# Date 1312909603 -3600
# Node ID ae10d7804168c185166277bcef3b18ffc9227b66
# Parent aca07ff1f0a59cc7ebb5ef76875229b7e99ba3ff
ACPI ERST: Revert change to erst_check_table() to be more permissive.

Permits tables that apparently Xen cannot handle (causes boot failure
on many systems).

Signed-off-by: Keir Fraser <keir@xxxxxxx>

diff -r aca07ff1f0a5 -r ae10d7804168 xen/drivers/acpi/apei/erst.c
--- a/xen/drivers/acpi/apei/erst.c Tue Aug 09 17:48:16 2011 +0100
+++ b/xen/drivers/acpi/apei/erst.c Tue Aug 09 18:06:43 2011 +0100
@@ -715,13 +715,7 @@

static int __init erst_check_table(struct acpi_table_erst *erst_tab)
{
- /*
- * Some old BIOSes include the ACPI standard header in the ERST header
- * length; new BIOSes do not. Our check allows for both methods.
- */
- if ((erst_tab->header_length !=
- (sizeof(struct acpi_table_erst) - sizeof(erst_tab->header)))
- && (erst_tab->header_length != sizeof(struct acpi_table_erst)))
+ if (erst_tab->header_length != sizeof(struct acpi_table_erst))
return -EINVAL;
if (erst_tab->header.length < sizeof(struct acpi_table_erst))
return -EINVAL;


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