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| author | Juergen Gross <jgross@suse.com> | 2018-10-10 08:14:55 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-10-10 10:44:22 +0200 |
| commit | ae7e1238e68f2a472a125673ab506d49158c1889 (patch) | |
| tree | 3ce290f2e5751224770e5f8449c34a43a29bd845 /arch/x86/include/uapi | |
| parent | 357d291ce035d1b757568058f3c9898c60d125b1 (diff) | |
| download | linux-0-day-ae7e1238e68f2a472a125673ab506d49158c1889.tar.gz linux-0-day-ae7e1238e68f2a472a125673ab506d49158c1889.tar.xz | |
x86/boot: Add ACPI RSDP address to setup_header
Xen PVH guests receive the address of the RSDP table from Xen. In order
to support booting a Xen PVH guest via Grub2 using the standard x86
boot entry we need a way for Grub2 to pass the RSDP address to the
kernel.
For this purpose expand the struct setup_header to hold the physical
address of the RSDP address. Being zero means it isn't specified and
has to be located the legacy way (searching through low memory or
EBDA).
While documenting the new setup_header layout and protocol version
2.14 add the missing documentation of protocol version 2.13.
There are Grub2 versions in several distros with a downstream patch
violating the boot protocol by writing past the end of setup_header.
This requires another update of the boot protocol to enable the kernel
to distinguish between a specified RSDP address and one filled with
garbage by such a broken Grub2.
From protocol 2.14 on Grub2 will write the version it is supporting
(but never a higher value than found to be supported by the kernel)
ored with 0x8000 to the version field of setup_header. This enables
the kernel to know up to which field Grub2 has written information
to. All fields after that are supposed to be clobbered.
Signed-off-by: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: boris.ostrovsky@oracle.com
Cc: bp@alien8.de
Cc: corbet@lwn.net
Cc: linux-doc@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/20181010061456.22238-3-jgross@suse.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/uapi')
| -rw-r--r-- | arch/x86/include/uapi/asm/bootparam.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h index a06cbf0197446..22f89d040dddc 100644 --- a/arch/x86/include/uapi/asm/bootparam.h +++ b/arch/x86/include/uapi/asm/bootparam.h @@ -16,6 +16,9 @@ #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) @@ -86,6 +89,7 @@ struct setup_header { __u64 pref_address; __u32 init_size; __u32 handover_offset; + __u64 acpi_rsdp_addr; } __attribute__((packed)); struct sys_desc_table { |