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pnor_layout.md

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About this document

This document gathers known information about partition layout in the original PNOR image from the Talos II platform.

Partition table

PNOR contains partition table at offset 0. It is constructed out of header and multiple entries. Refer to the ffs source code for more detailed information.

 struct ffs_hdr {
    uint32_t         magic;         // @magic:          Eye catcher/corruption detector
                                    //                  should always contain 0x50415254 or text PART
    uint32_t         version;       // @version:        Version of the structure
    uint32_t         size;          // @size:           Size of partition table (in block_size)
    uint32_t         entry_size;    // @entry_size:     Size of struct ffs_entry element (in bytes)
    uint32_t         entry_count;   // @entry_count:    Number of struct ffs_entry elements in @entries array
    uint32_t         block_size;    // @block_size:     Size of block on device (in bytes)
    uint32_t         block_count;   // @block_count:    Number of blocks on device
    uint32_t         resvd[4];      // @resvd:          Reserved words for future use
    uint32_t         checksum;      // @checksum:       Header checksum
    struct ffs_entry entries[];     // @entries:        Pointer to array of partition entries
} __attribute__ ((packed));

struct ffs_entry {
    char     name[16];      // @name:       Opaque null terminated string
    uint32_t base;          // @base:       Starting offset of partition in flash (in hdr.block_size)
    uint32_t size;          // @size:       Partition size (in hdr.block_size)
    uint32_t pid;           // @pid:        Parent partition entry (0xFFFFFFFF for toplevel)
    uint32_t id;            // @id:         Partition entry ID [1..65536]
    uint32_t type;          // @type:       Describe type of partition
    uint32_t flags;         // @flags:      Partition attributes (optional)
    uint32_t actual;        // @actual:     Actual partition size (in bytes)
    uint32_t resvd[4];      // @resvd:      Reserved words for future use
    struct {
        uint32_t data[16];  // @user:       User data (optional)
    } user;
    uint32_t checksum;      // @checksum:   Partition entry checksum (includes all above)
} __attribute__ ((packed));

Each partiton can contain image of following types:

  • FFS_TYPE_DATA
  • FFS_TYPE_LOGICAL
  • FFS_TYPE_PARTITION

Partition layout

Data presented below was extracted using ./fcp -L file:flash.pnor -o 0 and enchanced with additional data extracted directly from flash.pnor. More on how to use this tool can be found in porting.md#ffs-tools.

Partition Table Version: 1 Size: 2 * 0x1000 (block size) Block Count: 0x4000 Entry Size: 0x80 Number of entries: 0x21

Name ID Offset:End Size (bytes) Type Flags Actual size coreboot usage
part 0x01 0x00000000:0x00001FFF 0x2000 p p same as size Partition table
HBEL 0x02 0x00008000:0x0002BFFF 0x24000 d - same as size None
GUARD 0x03 0x0002C000:0x00030FFF 0x5000 d - same as size None
NVRAM 0x04 0x00031000:0x000C0FFF 0x90000 d - same as size Required
SECBOOT 0x05 0x000C1000:0x000E4FFF 0x24000 d - same as size None
DJVPD 0x06 0x000E5000:0x0012CFFF 0x48000 d - same as size None
MVPD 0x07 0x0012D000:0x001BCFFF 0x90000 d - same as size None
CVPD 0x08 0x001BD000:0x00204FFF 0x48000 d - same as size None
HBB 0x09 0x00205000:0x00304FFF 0x100000 d - same as size bootblock
HBD 0x0A 0x00305000:0x00424FFF 0x120000 d - same as size None
HBI 0x0B 0x00425000:0x019C4FFF 0x15A0000 d - same as size romstage, ramstage, payload (skiboot)
SBE 0x0C 0x019C5000:0x01A80FFF 0xBC000 d - same as size None
HCODE 0x0D 0x01A81000:0x01BA0FFF 0x120000 d - same as size None
HBRT 0x0E 0x01BA1000:0x021A0FFF 0x600000 d - same as size None
PAYLOAD 0x0F 0x021A1000:0x022A0FFF 0x100000 d - same as size None
BOOTKERNEL 0x10 0x022A1000:0x03820FFF 0x1580000 d - same as size skiroot
OCC 0x11 0x03821000:0x03940FFF 0x120000 d - same as size None
FIRDATA 0x12 0x03941000:0x03943FFF 0x3000 d - same as size None
VERSION 0x13 0x03944000:0x03945FFF 0x2000 d - same as size skiboot verifies this, but just warns about mismatch
BMC_INV 0x14 0x03968000:0x03970FFF 0x9000 d - same as size None
HBBL 0x15 0x03971000:0x03977FFF 0x7000 d - same as size None
ATTR_TMP 0x16 0x03978000:0x0397FFFF 0x8000 d - same as size None
ATTR_PERM 0x17 0x03980000:0x03987FFF 0x8000 d - same as size None
IMA_CATALOG 0x18 0x03989000:0x039C8FFF 0x40000 d - same as size None
RINGOVD 0x19 0x039C9000:0x039E8FFF 0x20000 d - same as size None
WOFDATA 0x1A 0x039E9000:0x03CE8FFF 0x300000 d - same as size None
HB_VOLATILE 0x1B 0x03CE9000:0x03CEDFFF 0x5000 d - same as size None
MEMD 0x1C 0x03cee000:0x03CFBFFF 0xE000 d - same as size Memory configuration data
SBKT 0x1D 0x03d02000:0x03D05FFF 0x4000 d - same as size None
HDAT 0x1E 0x03d06000:0x03D0DFFF 0x8000 d - same as size None
UVISOR 0x1F 0x03d10000:0x03E0FFFF 0x100000 d - same as size None
BOOTKERNFW 0x20 0x03e10000:0x03FEFFFF 0x1E0000 d - same as size None
BACKUP_PART 0x21 0x03ff7000:0x03FFEFFF 0x8000 d - 0 Required

Note: If partition has no coreboot usage means that erasing this partition didn't prevent the platform from starting skiroot. Partition may still be used in some case or in the later stages of the booting process.

Type:

  • l = FFS_TYPE_LOGICAL
  • d = FFS_TYPE_DATA
  • p = FFS_TYPE_PARTITION

Flags:

  • b = FFS_FLAGS_U_BOOT_ENV
  • p = FFS_FLAGS_PROTECTED

Reproducibility

Reproducibility of partition content can be found at the wiki page.

Partition original usage

part

This partition contains partition table.

HBEL

This partition is used by hostboot to to save crash information for later debug. More information can be found at the wiki page.

GUARD

This partition is responsible for holding information about components that are detected as broken. More information about it can be found at the wiki page.

NVRAM

Non volatile memory required for OPAL systems. More information can be fouind on the wiki page.

SECBOOT

This partition is used to hold secure variables across renppts in tamper-resistant manner. Because writes to PNOR can't be prevented, hash of this partition is stored in the TPM NV, and verified at the boot time. More information can be found at the wiki page.

HBB

Bootloader code for hostboot

HBD

Hostboot data

HBI

Main hostboot application

SBE

Self Boot Engine, stored in module EEPROM

HCODE

FW for PPE

PAYLOAD

This partition contains skiboot.

BOOTKERNEL

This partition contains skiroot: Linux kernel bundled with initrd (Linux userspace and petitboot binaries).

OCC

Most likely contains FW for OCC (On Chip Controller). Source code for this FW is available here.

VERSION

Probably just an information about versions of a binaries in the PNOR image.

HBBL

This partition is used by hostboot during update operation.

IMA_CATALOG

This partition holds a list of events supported by OCC microcode.

MEMD

Holds memory configuration data.

HDAT

Holds inforamtions from hostboot similar to device-tree, but in hostboot-data format.

BOOTKERNFW

Proprietary AMD GPU FW was added here at Talos II System Package 2.00 release.

BACKUP_PART

Because Actual Size of this partition is 0, it doesn't take any space in PNOR image.