Flash Map (FMAP) is a simple specification for layout of flash devices. A reference implementation is available at flashmap git repo. Below is the FMAP defined for Pixel 2 / Samus, retrieved by running dump_fmap image.bin: fmap_signature __FMAP__ fmap_version: 1.0 fmap_base: 0x0 fmap_size: 0x00800000 (8388608) fmap_name: FMAP fmap_nareas: 33 >>> This section describes the attributes of this FMAP. Note that the Samus FW image size is 8MB. area: 1 area_offset: 0x00000000 area_size: 0x00200000 (2097152) area_name: SI_ALL >>> This region contains the SPI descriptor in a format defined by the on-chip SPI controller and Intel Management Engine. area: 2 area_offset: 0x00000000 area_size: 0x00001000 (4096) area_name: SI_DESC >>> SPI descriptor. area: 3 area_offset: 0x00001000 area_size: 0x001ff000 (2093056) area_name: SI_ME >>> Management Engine. area: 4 area_offset: 0x00200000 area_size: 0x00600000 (6291456) area_name: SI_BIOS >>> Non descriptor / ME region. area: 5 area_offset: 0x00200000 area_size: 0x000f0000 (983040) area_name: RW_SECTION_A >>> Region A of re-writable FW, which may be reflashed during auto-update. area: 6 area_offset: 0x00200000 area_size: 0x00010000 (65536) area_name: VBLOCK_A >>> Keyblock for RW Region A. area: 7 area_offset: 0x00210000 area_size: 0x000b0000 (720896) area_name: FW_MAIN_A >>> Rewritable ramstage BIOS image A. area: 8 area_offset: 0x002c0000 area_size: 0x00010000 (65536) area_name: PD_MAIN_A >>> PD MCU (USB-PD / USB-C power controller) EC image A. area: 9 area_offset: 0x002d0000 area_size: 0x0001ffc0 (131008) area_name: EC_MAIN_A >>> Main EC (Embedded Controller) image A. area: 10 area_offset: 0x002effc0 area_size: 0x00000040 (64) area_name: RW_FWID_A >>> ID string of rewritable ramstage BIOS image A. Eg. "Google_Samus.6300.174.0". area: 11 area_offset: 0x002f0000 area_size: 0x000f0000 (983040) area_name: RW_SECTION_B >>> Region B of re-writable FW. For redundancy / recovery on failed update. area: 12 area_offset: 0x002f0000 area_size: 0x00010000 (65536) area_name: VBLOCK_B area: 13 area_offset: 0x00300000 area_size: 0x000b0000 (720896) area_name: FW_MAIN_B area: 14 area_offset: 0x003b0000 area_size: 0x00010000 (65536) area_name: PD_MAIN_B area: 15 area_offset: 0x003c0000 area_size: 0x0001ffc0 (131008) area_name: EC_MAIN_B area: 16 area_offset: 0x003dffc0 area_size: 0x00000040 (64) area_name: RW_FWID_B >>> RW Region B. area: 17 area_offset: 0x003e0000 area_size: 0x00010000 (65536) area_name: RW_MRC_CACHE >>> Region that stores board DRAM timing information, written during initial memory training. area: 18 area_offset: 0x003f0000 area_size: 0x00004000 (16384) area_name: RW_ELOG >>> Event log. Normally exported and decoded on a Chromebook to /var/log/eventlog. area: 19 area_offset: 0x003f4000 area_size: 0x00004000 (16384) area_name: RW_SHARED area: 20 area_offset: 0x003f4000 area_size: 0x00002000 (8192) area_name: SHARED_DATA area: 21 area_offset: 0x003f6000 area_size: 0x00002000 (8192) area_name: VBLOCK_DEV >>> Shared FW data related to dev-mode FW verification. area: 22 area_offset: 0x003f8000 area_size: 0x00002000 (8192) area_name: RW_VPD >>> Writable vital product data, eg. first use date. area: 23 area_offset: 0x003fa000 area_size: 0x00006000 (24576) area_name: RW_UNUSED >>> Extra / unused space in RW region. area: 24 area_offset: 0x00400000 area_size: 0x00200000 (2097152) area_name: RW_LEGACY >>> Alternate OtherOS payload, normally for booting SeaBIOS. area: 25 area_offset: 0x00600000 area_size: 0x00200000 (2097152) area_name: WP_RO >>> RO region of FW - written once at the factory and (normally) never again. area: 26 area_offset: 0x00600000 area_size: 0x00004000 (16384) area_name: RO_VPD >>> RO vital product data, eg. sensor calibration data, keyboard / region information. area: 27 area_offset: 0x00604000 area_size: 0x0000c000 (49152) area_name: RO_UNUSED >> Extra . unused space. area: 28 area_offset: 0x00610000 area_size: 0x001f0000 (2031616) area_name: RO_SECTION >>> RO FW region. area: 29 area_offset: 0x00610000 area_size: 0x00000800 (2048) area_name: FMAP >> Data structure that describes what you're looking at right now :) area: 30 area_offset: 0x00610800 area_size: 0x00000040 (64) area_name: RO_FRID >>> ID string of RO BIOS image. Eg. "Google_Samus.6300.174.0". area: 31 area_offset: 0x00610840 area_size: 0x000007c0 (1984) area_name: RO_FRID_PAD >>> For alignment of RO_FRID / GBB??? area: 32 area_offset: 0x00611000 area_size: 0x000ef000 (978944) area_name: GBB >>> Google Binary Block. Stores key information, FW screen bitmaps, and special developer flags that can be set to modify boot behavior. area: 33 area_offset: 0x00700000 area_size: 0x00100000 (1048576) area_name: BOOT_STUB >>> RO Coreboot - Ramstage, romstage, CBFS, etc. |
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