[coreboot] [PATCH] Update the document of CBFS

[Hamo]

CBFS document is a little old since the structure of it has changed a
lot specially CBFS master header.
This patch updated  the document to show the newest structure of CBFS.

Signed-off-by: Yang Bai <hamo.by at gmail.com>

Index: documentation/cbfs.txt
===================================================================
--- documentation/cbfs.txt	(revision 6534)
+++ documentation/cbfs.txt	(working copy)
@@ -144,10 +144,13 @@
 The following is the structure of the master header:

 struct cbfs_header {
-	unsigned int magic;
-	unsigned int size;
-	unsigned int align;
-	unsigned int offset;
+	u32 magic;
+        u32 version;
+        u32 romsize;
+        u32 bootblocksize;
+	u32 align;
+	u32 offset;
+	u32 pad[2];
 };

 The meaning of each member is as follows:
@@ -156,9 +159,14 @@
 magic
 number is 0x4F524243, which is 'ORBC' in ASCII.

-'size' is the size of the ROM in bytes.  Coreboot will subtract 'size' from
+'version' is a 32 bit number that shows the version of CBFS master header.
+Since only one version exists now, it should always be 0x31313131.
+
+'romsize' is the size of the ROM in bytes.  Coreboot will subtract
'romsize' from
 0xFFFFFFFF to locate the beginning of the ROM in memory.

+'bootblocksize' is the size of the bootblock in bytes.
+
 'align' is the number of bytes that each component is aligned to within the
 ROM.  This is used to make sure that each component is aligned correctly
 with
@@ -193,11 +201,11 @@
 Each CBFS component starts with a header:

 struct cbfs_file {
-         char magic[8];
-         unsigned int len;
-         unsigned int type;
-         unsigned int checksum;
-         unsigned int offset;
+	char magic[8];
+	u32 len;
+	u32 type;
+	u32 checksum;
+	u32 offset;
 };

 'magic' is a magic value used to identify the header.  During runtime,
@@ -287,11 +295,11 @@
 The header is defined as:

 struct cbfs_stage {
-         unsigned int compression;
-         unsigned long long entry;
-         unsigned long long load;
-         unsigned int len;
-         unsigned int memlen;
+	u32 compression;  /** Compression type */
+	u64 entry;  /** entry point */
+	u64 load;   /** Where to load in memory */
+	u32 len;          /** length of data to load */
+	u32 memlen;	   /** total length of object in memory */
 };

 'compression' is an integer defining how the data is compressed.  There
@@ -355,12 +363,12 @@
 The following is the structure of each segment header:

 struct cbfs_payload_segment {
-         unsigned int type;
-         unsigned int compression;
-         unsigned int offset;
-         unsigned long long load_addr;
-         unsigned int len;
-         unsigned int mem_len;
+	u32 type;
+	u32 compression;
+	u32 offset;
+	u64 load_addr;
+	u32 len;
+	u32 mem_len;
 };

 'type' is the type of segment, one of the following:



-- 
    """
    Keep It Simple,Stupid.
    """

Chinese Name: 白杨
Nick Name: Hamo
Homepage: http://hamobai.com/
GPG KEY ID: 0xA4691A33
Key fingerprint = 09D5 2D78 8E2B 0995 CF8E  4331 33C4 3D24 A469 1A33