From c1adeb68a0228a514f68baec89994ec77a1311fe Mon Sep 17 00:00:00 2001 From: Duncan Laurie Date: Wed, 29 Apr 2020 00:04:14 -0700 Subject: arch/x86/acpi_device: Allow empty child references Currently if a child table is created and added to a property list without adding any properties to that child it will generate an empty package. For example: struct acpi_dp *dsd = acpi_dp_new_table("_DSD"); struct acpi_dp *prop = acpi_dp_new_table("PROP"); acpi_dp_add_child(dsd, "dsd-prop", prop); acpi_dp_write(dsd); Results in an empty PROP package: Name (_DSD, Package (2) { ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b") Package (1) { Package (2) { "dsd-prop", "PROP" } } } Name (PROP, Package (0) { } Empty packages don't seem to be explicitly forbidden, but they don't serve a purpose with device properties. Instead, if packages without any properties or children are skipped then this empty package is not written and the added child property can refer to another property that is already defined. This allows creating property references to existing tables, which can save duplication and namespace collision issues with nested properties. BUG=b:146482091 Signed-off-by: Duncan Laurie Change-Id: I9fee2ceb8a4496b90c7210533eee8c2b186cdfff Reviewed-on: https://review.coreboot.org/c/coreboot/+/40880 Tested-by: build bot (Jenkins) Reviewed-by: Furquan Shaikh --- src/arch/x86/acpi_device.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'src/arch') diff --git a/src/arch/x86/acpi_device.c b/src/arch/x86/acpi_device.c index b4016ef5db..f3ee1e7ec4 100644 --- a/src/arch/x86/acpi_device.c +++ b/src/arch/x86/acpi_device.c @@ -665,7 +665,7 @@ void acpi_dp_write(struct acpi_dp *table) char *dp_count, *prop_count = NULL; int child_count = 0; - if (!table || table->type != ACPI_DP_TYPE_TABLE) + if (!table || table->type != ACPI_DP_TYPE_TABLE || !table->next) return; /* Name (name) */ -- cgit v1.2.3