1 files changed, 142 insertions, 0 deletions
diff --git a/tools/binman/README.entries b/tools/binman/README.entries
index 9a316763ac..2e6aea1e84 100644
--- a/tools/binman/README.entries
+++ b/tools/binman/README.entries
@@ -60,6 +60,148 @@ See cros_ec_rw for an example of this.
 
 
 
+Entry: cbfs: Entry containing a Coreboot Filesystem (CBFS)
+----------------------------------------------------------
+
+A CBFS provides a way to group files into a group. It has a simple directory
+structure and allows the position of individual files to be set, since it is
+designed to support execute-in-place in an x86 SPI-flash device. Where XIP
+is not used, it supports compression and storing ELF files.
+
+CBFS is used by coreboot as its way of orgnanising SPI-flash contents.
+
+The contents of the CBFS are defined by subnodes of the cbfs entry, e.g.:
+
+    cbfs {
+        size = <0x100000>;
+        u-boot {
+            cbfs-type = "raw";
+        };
+        u-boot-dtb {
+            cbfs-type = "raw";
+        };
+    };
+
+This creates a CBFS 1MB in size two files in it: u-boot.bin and u-boot.dtb.
+Note that the size is required since binman does not support calculating it.
+The contents of each entry is just what binman would normally provide if it
+were not a CBFS node. A blob type can be used to import arbitrary files as
+with the second subnode below:
+
+    cbfs {
+        size = <0x100000>;
+        u-boot {
+            cbfs-name = "BOOT";
+            cbfs-type = "raw";
+        };
+
+        dtb {
+            type = "blob";
+            filename = "u-boot.dtb";
+            cbfs-type = "raw";
+            cbfs-compress = "lz4";
+        };
+    };
+
+This creates a CBFS 1MB in size with u-boot.bin (named "BOOT") and
+u-boot.dtb (named "dtb") and compressed with the lz4 algorithm.
+
+
+Properties supported in the top-level CBFS node:
+
+cbfs-arch:
+    Defaults to "x86", but you can specify the architecture if needed.
+
+
+Properties supported in the CBFS entry subnodes:
+
+cbfs-name:
+    This is the name of the file created in CBFS. It defaults to the entry
+    name (which is the node name), but you can override it with this
+    property.
+
+cbfs-type:
+    This is the CBFS file type. The following are supported:
+
+    raw:
+        This is a 'raw' file, although compression is supported. It can be
+        used to store any file in CBFS.
+
+    stage:
+        This is an ELF file that has been loaded (i.e. mapped to memory), so
+        appears in the CBFS as a flat binary. The input file must be an ELF
+        image, for example this puts "u-boot" (the ELF image) into a 'stage'
+        entry:
+
+            cbfs {
+                size = <0x100000>;
+                u-boot-elf {
+                    cbfs-name = "BOOT";
+                    cbfs-type = "stage";
+                };
+            };
+
+        You can use your own ELF file with something like:
+
+            cbfs {
+                size = <0x100000>;
+                something {
+                    type = "blob";
+                    filename = "cbfs-stage.elf";
+                    cbfs-type = "stage";
+                };
+            };
+
+        As mentioned, the file is converted to a flat binary, so it is
+        equivalent to adding "u-boot.bin", for example, but with the load and
+        start addresses specified by the ELF. At present there is no option
+        to add a flat binary with a load/start address, similar to the
+        'add-flat-binary' option in cbfstool.
+
+
+The current implementation supports only a subset of CBFS features. It does
+not support other file types (e.g. payload), adding multiple files (like the
+'files' entry with a pattern supported by binman), putting files at a
+particular offset in the CBFS and a few other things.
+
+Of course binman can create images containing multiple CBFSs, simply by
+defining these in the binman config:
+
+
+    binman {
+        size = <0x800000>;
+        cbfs {
+            offset = <0x100000>;
+            size = <0x100000>;
+            u-boot {
+                cbfs-type = "raw";
+            };
+            u-boot-dtb {
+                cbfs-type = "raw";
+            };
+        };
+
+        cbfs2 {
+            offset = <0x700000>;
+            size = <0x100000>;
+            u-boot {
+                cbfs-type = "raw";
+            };
+            u-boot-dtb {
+                cbfs-type = "raw";
+            };
+            image {
+                type = "blob";
+                filename = "image.jpg";
+            };
+        };
+    };
+
+This creates an 8MB image with two CBFSs, one at offset 1MB, one at 7MB,
+both of size 1MB.
+
+
+
 Entry: cros-ec-rw: A blob entry which contains a Chromium OS read-write EC image
 --------------------------------------------------------------------------------