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Commit fb884381 authored by Huang, Ying's avatar Huang, Ying Committed by Ingo Molnar
Browse files

x86, boot: Document for linked list of struct setup_data 



Documentation for linked list of struct setup_data.

Signed-off-by: default avatarHuang Ying <ying.huang@intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent c14b2adf

Documentation/i386/boot.txt

+26 −0
Original line number Diff line number Diff line
@@ -42,6 +42,8 @@ Protocol 2.05: (Kernel 2.6.20) Make protected mode kernel relocatable. 
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 @@ Offset Proto Name Meaning 
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 @@ command line is entered using the following protocol: 
	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