[S] Change in coreboot[main]: arch/x86: Shadow ROM tables into EBDA

[Shuo Liu (Code Review)]

Attention is currently required from: Chen, Gang C, Jincheng Li, Jérémy Compostella.

Hello Chen, Gang C, Jincheng Li,

I'd like you to do a code review.
Please visit

https://review.coreboot.org/c/coreboot/+/84322?usp=email

to review the following change.

Change subject: arch/x86: Shadow ROM tables into EBDA
......................................................................

arch/x86: Shadow ROM tables into EBDA

For platforms without writable PAM-F segment support (e.g. some
simics virtual platforms), put ROM table pointers (e.g. ACPI/SMBIOS
low pointers) into EBDA.

Signed-off-by: Shuo Liu 
Signed-off-by: Gang Chen 
Signed-off-by: Jincheng Li 
Change-Id: I2aac74708279813f9a848044d470fdc980ea4305
---
M src/arch/x86/Kconfig
M src/arch/x86/tables.c
2 files changed, 17 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/22/84322/1

diff --git a/src/arch/x86/Kconfig b/src/arch/x86/Kconfig
index cc68f5c..d6434ae 100644
--- a/src/arch/x86/Kconfig
+++ b/src/arch/x86/Kconfig
@@ -439,4 +439,11 @@
    default 0x400
    help
      The default value of EBDA size is 0x400.
+
+config SHADOW_ROM_TABLE_TO_EBDA
+	bool "Shadow ROM tables to EBDA"
+	default n
+	help
+	  For platforms without writable PAM-F segment support. Put ROM table
+	  pointers (e.g. ACPI/SMBIOS low pointers) into EBDA.
 endif
diff --git a/src/arch/x86/tables.c b/src/arch/x86/tables.c
index 2732638..e47f1bc 100644
--- a/src/arch/x86/tables.c
+++ b/src/arch/x86/tables.c
@@ -192,7 +192,12 @@
 void arch_write_tables(uintptr_t coreboot_table)
 {
    size_t sz;
-	unsigned long rom_table_end = 0xf0000;
+	unsigned long rom_table_end;
+
+	if (CONFIG(SHADOW_ROM_TABLE_TO_EBDA))
+		rom_table_end = CONFIG_DEFAULT_EBDA_SEGMENT << 4;
+	else
+		rom_table_end = 0xf0000;

/* This table must be between 0x0f0000 and 0x100000 */
    if (CONFIG(GENERATE_PIRQ_TABLE))
@@ -224,4 +229,8 @@
    const uintptr_t base = 0;

bootmem_add_range(base, forwarding_table - base, BM_MEM_TABLE);
+
+	/* Reserve Extend BIOS Data Area (EBDA) region explicitly */
+	bootmem_add_range((uintptr_t)CONFIG_DEFAULT_EBDA_SEGMENT << 4,
+			CONFIG_DEFAULT_EBDA_SIZE, BM_MEM_TABLE);
 }