Change in coreboot[master]: arch/x86/smbios.c: Allow creating entries for empty DIMM slots

[Angel Pons (Code Review)]

Angel Pons has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/64035 )

Change subject: arch/x86/smbios.c: Allow creating entries for empty DIMM slots
......................................................................

arch/x86/smbios.c: Allow creating entries for empty DIMM slots

Properly handle meminfo DIMMs with `dimm_size` of 0, which represent
empty slots. This allows platform code to create dummy meminfo DIMMs
so that SMBIOS tables have type 17 entries for empty DIMM slots.

Change-Id: I17ae83edf94483bd2eeef5524ff82721c196b8ba
Signed-off-by: Angel Pons 
---
M src/arch/x86/smbios.c
1 file changed, 34 insertions(+), 3 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/35/64035/1

diff --git a/src/arch/x86/smbios.c b/src/arch/x86/smbios.c
index c48ce86..c0057b6 100644
--- a/src/arch/x86/smbios.c
+++ b/src/arch/x86/smbios.c
@@ -277,6 +277,30 @@
    return smbios_full_table_len(&t->header, t->eos);
 }

+static int create_smbios_type17_for_empty_slot(struct dimm_info *dimm,
+					       unsigned long *current, int *handle,
+					       int type16_handle)
+{
+	struct smbios_type17 *t = smbios_carve_table(*current, SMBIOS_MEMORY_DEVICE,
+						     sizeof(*t), *handle);
+	t->phys_memory_array_handle = type16_handle;
+	/* no handle for error information */
+	t->memory_error_information_handle = 0xfffe;
+	t->total_width = 0xffff; /* Unknown */
+	t->data_width = 0xffff; /* Unknown */
+	t->form_factor = 0x2; /* Unknown */
+	smbios_fill_dimm_locator(dimm, t); /* Device and Bank */
+	t->memory_type = 0x2; /* Unknown */
+	t->type_detail = 0x2; /* Unknown */
+	t->manufacturer = smbios_add_string(t->eos, "NO DIMM");
+	t->serial_number = smbios_add_string(t->eos, "NO DIMM");
+	t->asset_tag = smbios_add_string(t->eos, "NO DIMM");
+	t->part_number = smbios_add_string(t->eos, "NO DIMM");
+
+	*handle += 1;
+	return smbios_full_table_len(&t->header, t->eos);
+}
+
 #define VERSION_VPD "firmware_version"
 static const char *vpd_get_bios_version(void)
 {
@@ -944,15 +968,19 @@

printk(BIOS_INFO, "Create SMBIOS type 17\n");
    for (i = 0; i < meminfo->dimm_cnt && i < ARRAY_SIZE(meminfo->dimm); i++) {
-		struct dimm_info *dimm;
-		dimm = &meminfo->dimm[i];
+		struct dimm_info *d = &meminfo->dimm[i];
    	/*
    	 * Windows 10 GetPhysicallyInstalledSystemMemory functions reads SMBIOS tables
    	 * type 16 and type 17. The type 17 tables need to point to a type 16 table.
    	 * Otherwise, the physical installed memory size is guessed from the system
    	 * memory map, which results in a slightly smaller value than the actual size.
    	 */
-		const int len = create_smbios_type17_for_dimm(dimm, current, handle, type16);
+		int len;
+		if (d->dimm_size > 0)
+			len = create_smbios_type17_for_dimm(d, current, handle, type16);
+		else
+			len = create_smbios_type17_for_empty_slot(d, current, handle, type16);
+
    	*current += len;
    	totallen += len;
    }
@@ -1043,6 +1071,9 @@
    for (i = 0; i < meminfo->dimm_cnt && i < ARRAY_SIZE(meminfo->dimm); i++) {
    	struct dimm_info *dimm;
    	dimm = &meminfo->dimm[i];
+		if (dimm->dimm_size == 0)
+			continue;
+
    	u32 end_addr = start_addr + (dimm->dimm_size << 10) - 1;
    	totallen += smbios_write_type20_table(current, handle, start_addr, end_addr,
    			type17_handle, type19_handle);