x86: zImage: Propagate acpi_rsdp_addr to kernel via boot parameters

This is reincarnation of the U-Boot

commit 3469bf42
Author: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Date:   Wed Jan 10 19:40:15 2018 +0200

    x86: zImage: Propagate acpi_rsdp_addr to kernel via boot parameters

after upstream got eventually the Linux kernel

commit e6e094e053af75cbc164e950814d3d084fb1e698
Author: Juergen Gross <jgross@suse.com>
Date:   Tue Nov 20 08:25:29 2018 +0100

    x86/acpi, x86/boot: Take RSDP address from boot params if available
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: NBin Meng <bmeng.cn@gmail.com>

arch/x86/include/asm/bootparam.h

@@ -94,7 +94,8 @@ struct boot_params {
 	__u8  _pad2[4];					/* 0x054 */
 	__u64  tboot_addr;				/* 0x058 */
 	struct ist_info ist_info;			/* 0x060 */
-	__u8  _pad3[16];				/* 0x070 */
+	__u64 acpi_rsdp_addr;				/* 0x070 */
+	__u8  _pad3[8];					/* 0x078 */
 	__u8  hd0_info[16];	/* obsolete! */		/* 0x080 */
 	__u8  hd1_info[16];	/* obsolete! */		/* 0x090 */
 	struct sys_desc_table sys_desc_table;		/* 0x0a0 */

arch/x86/lib/zimage.c

@@ -288,6 +288,10 @@ int setup_zimage(struct boot_params *setup_base, char *cmd_line, int auto_boot,
 		hdr->hardware_subarch = X86_SUBARCH_INTEL_MID;
 #endif
 
+#ifdef CONFIG_GENERATE_ACPI_TABLE
+	setup_base->acpi_rsdp_addr = acpi_get_rsdp_addr();
+#endif
+
 	setup_device_tree(hdr, (const void *)env_get_hex("fdtaddr", 0));
 	setup_video(&setup_base->screen_info);