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[Xen-devel] [PATCH 1/2] x86/boot: revert commit ae7e1238e68f2a (Add ACPI RSDP address to setup_header)



Peter Anvin pointed out that commit ae7e1238e68f2a ("x86/boot: Add
ACPI RSDP address to setup_header") should be reverted as setup_header
should contain only items set by legacy BIOS.

So revert said commit. Instead of fully reverting the depending
commit e7b66d16fe4172 ("x86/acpi, x86/boot: Take RSDP address for boot
params if available") just remove the setup_header reference in order
to replace it by a boot_params in a followup patch.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 Documentation/x86/boot.txt            | 32 +-------------------------------
 arch/x86/boot/header.S                |  6 +-----
 arch/x86/include/asm/x86_init.h       |  2 --
 arch/x86/include/uapi/asm/bootparam.h |  4 ----
 arch/x86/kernel/acpi/boot.c           |  2 +-
 arch/x86/kernel/head32.c              |  1 -
 arch/x86/kernel/head64.c              |  2 --
 arch/x86/kernel/setup.c               | 17 -----------------
 8 files changed, 3 insertions(+), 63 deletions(-)

diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt
index 7727db8f94bc..5e9b826b5f62 100644
--- a/Documentation/x86/boot.txt
+++ b/Documentation/x86/boot.txt
@@ -61,18 +61,6 @@ Protocol 2.12:       (Kernel 3.8) Added the xloadflags field 
and extension fields
                to struct boot_params for loading bzImage and ramdisk
                above 4G in 64bit.
 
-Protocol 2.13: (Kernel 3.14) Support 32- and 64-bit flags being set in
-               xloadflags to support booting a 64-bit kernel from 32-bit
-               EFI
-
-Protocol 2.14: (Kernel 4.20) Added acpi_rsdp_addr holding the physical
-               address of the ACPI RSDP table.
-               The bootloader updates version with:
-               0x8000 | min(kernel-version, bootloader-version)
-               kernel-version being the protocol version supported by
-               the kernel and bootloader-version the protocol version
-               supported by the bootloader.
-
 **** MEMORY LAYOUT
 
 The traditional memory map for the kernel loader, used for Image or
@@ -209,7 +197,6 @@ Offset      Proto   Name            Meaning
 0258/8 2.10+   pref_address    Preferred loading address
 0260/4 2.10+   init_size       Linear memory required during initialization
 0264/4 2.11+   handover_offset Offset of handover entry point
-0268/8 2.14+   acpi_rsdp_addr  Physical address of RSDP table
 
 (1) For backwards compatibility, if the setup_sects field contains 0, the
     real value is 4.
@@ -322,7 +309,7 @@ Protocol:   2.00+
   Contains the magic number "HdrS" (0x53726448).
 
 Field name:    version
-Type:          modify
+Type:          read
 Offset/size:   0x206/2
 Protocol:      2.00+
 
@@ -330,12 +317,6 @@ Protocol:  2.00+
   e.g. 0x0204 for version 2.04, and 0x0a11 for a hypothetical version
   10.17.
 
-  Up to protocol version 2.13 this information is only read by the
-  bootloader. From protocol version 2.14 onwards the bootloader will
-  write the used protocol version or-ed with 0x8000 to the field. The
-  used protocol version will be the minimum of the supported protocol
-  versions of the bootloader and the kernel.
-
 Field name:    realmode_swtch
 Type:          modify (optional)
 Offset/size:   0x208/4
@@ -763,17 +744,6 @@ Offset/size:       0x264/4
 
   See EFI HANDOVER PROTOCOL below for more details.
 
-Field name:    acpi_rsdp_addr
-Type:          write
-Offset/size:   0x268/8
-Protocol:      2.14+
-
-  This field can be set by the boot loader to tell the kernel the
-  physical address of the ACPI RSDP table.
-
-  A value of 0 indicates the kernel should fall back to the standard
-  methods to locate the RSDP.
-
 
 **** THE IMAGE CHECKSUM
 
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 4c881c850125..850b8762e889 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -300,7 +300,7 @@ _start:
        # Part 2 of the header, from the old setup.S
 
                .ascii  "HdrS"          # header signature
-               .word   0x020e          # header version number (>= 0x0105)
+               .word   0x020d          # header version number (>= 0x0105)
                                        # or else old loadlin-1.5 will fail)
                .globl realmode_swtch
 realmode_swtch:        .word   0, 0            # default_switch, SETUPSEG
@@ -558,10 +558,6 @@ pref_address:              .quad LOAD_PHYSICAL_ADDR        
# preferred load addr
 init_size:             .long INIT_SIZE         # kernel initialization size
 handover_offset:       .long 0                 # Filled in by build.c
 
-acpi_rsdp_addr:                .quad 0                 # 64-bit physical 
pointer to the
-                                               # ACPI RSDP table, added with
-                                               # version 2.14
-
 # End of setup header #####################################################
 
        .section ".entrytext", "ax"
diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index 0f842104862c..b85a7c54c6a1 100644
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -303,6 +303,4 @@ extern void x86_init_noop(void);
 extern void x86_init_uint_noop(unsigned int unused);
 extern bool x86_pnpbios_disabled(void);
 
-void x86_verify_bootdata_version(void);
-
 #endif
diff --git a/arch/x86/include/uapi/asm/bootparam.h 
b/arch/x86/include/uapi/asm/bootparam.h
index 22f89d040ddd..a06cbf019744 100644
--- a/arch/x86/include/uapi/asm/bootparam.h
+++ b/arch/x86/include/uapi/asm/bootparam.h
@@ -16,9 +16,6 @@
 #define RAMDISK_PROMPT_FLAG            0x8000
 #define RAMDISK_LOAD_FLAG              0x4000
 
-/* version flags */
-#define VERSION_WRITTEN        0x8000
-
 /* loadflags */
 #define LOADED_HIGH    (1<<0)
 #define KASLR_FLAG     (1<<1)
@@ -89,7 +86,6 @@ struct setup_header {
        __u64   pref_address;
        __u32   init_size;
        __u32   handover_offset;
-       __u64   acpi_rsdp_addr;
 } __attribute__((packed));
 
 struct sys_desc_table {
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 92c76bf97ad8..fb3b1f3a5aba 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -1776,5 +1776,5 @@ void __init arch_reserve_mem_area(acpi_physical_address 
addr, size_t size)
 
 u64 x86_default_get_root_pointer(void)
 {
-       return boot_params.hdr.acpi_rsdp_addr;
+       return 0;
 }
diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
index 76fa3b836598..ec6fefbfd3c0 100644
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -37,7 +37,6 @@ asmlinkage __visible void __init i386_start_kernel(void)
        cr4_init_shadow();
 
        sanitize_boot_params(&boot_params);
-       x86_verify_bootdata_version();
 
        x86_early_init_platform_quirks();
 
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 7663a8eb602b..16b1cbd3a61e 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -457,8 +457,6 @@ void __init x86_64_start_reservations(char *real_mode_data)
        if (!boot_params.hdr.version)
                copy_bootdata(__va(real_mode_data));
 
-       x86_verify_bootdata_version();
-
        x86_early_init_platform_quirks();
 
        switch (boot_params.hdr.hardware_subarch) {
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index b74e7bfed6ab..d494b9bfe618 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1280,23 +1280,6 @@ void __init setup_arch(char **cmdline_p)
        unwind_init();
 }
 
-/*
- * From boot protocol 2.14 onwards we expect the bootloader to set the
- * version to "0x8000 | <used version>". In case we find a version >= 2.14
- * without the 0x8000 we assume the boot loader supports 2.13 only and
- * reset the version accordingly. The 0x8000 flag is removed in any case.
- */
-void __init x86_verify_bootdata_version(void)
-{
-       if (boot_params.hdr.version & VERSION_WRITTEN)
-               boot_params.hdr.version &= ~VERSION_WRITTEN;
-       else if (boot_params.hdr.version >= 0x020e)
-               boot_params.hdr.version = 0x020d;
-
-       if (boot_params.hdr.version < 0x020e)
-               boot_params.hdr.acpi_rsdp_addr = 0;
-}
-
 #ifdef CONFIG_X86_32
 
 static struct resource video_ram_resource = {
-- 
2.16.4


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