x86, boot: Document for linked list of struct setup_data
Documentation for linked list of struct setup_data.
Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/Documentation/i386/boot.txt b/Documentation/i386/boot.txt
index 2eb1610..0fac346 100644
--- a/Documentation/i386/boot.txt
+++ b/Documentation/i386/boot.txt
@@ -42,6 +42,8 @@
Protocol 2.06: (Kernel 2.6.22) Added a field that contains the size of
the boot command line
+Protocol 2.09: (kernel 2.6.26) Added a field of 64-bit physical
+ pointer to single linked list of struct setup_data.
**** MEMORY LAYOUT
@@ -172,6 +174,8 @@
0240/8 2.07+ hardware_subarch_data Subarchitecture-specific data
0248/4 2.08+ payload_offset Offset of kernel payload
024C/4 2.08+ payload_length Length of kernel payload
+0250/8 2.09+ setup_data 64-bit physical pointer to linked list
+ of struct setup_data
(1) For backwards compatibility, if the setup_sects field contains 0, the
real value is 4.
@@ -572,6 +576,28 @@
covered by setup_move_size, so you may need to adjust this
field.
+Field name: setup_data
+Type: write (obligatory)
+Offset/size: 0x250/8
+Protocol: 2.09+
+
+ The 64-bit physical pointer to NULL terminated single linked list of
+ struct setup_data. This is used to define a more extensible boot
+ parameters passing mechanism. The definition of struct setup_data is
+ as follow:
+
+ struct setup_data {
+ u64 next;
+ u32 type;
+ u32 len;
+ u8 data[0];
+ };
+
+ Where, the next is a 64-bit physical pointer to the next node of
+ linked list, the next field of the last node is 0; the type is used
+ to identify the contents of data; the len is the length of data
+ field; the data holds the real payload.
+
**** MEMORY LAYOUT OF THE REAL-MODE CODE