Versioning¶

SBL implements a simple versioning structure with many features:

Image identification (e.g. supported platforms)
Core major and minor revision (See Semantic Versioning)
Project major and minor revision
Traceability to release process and build environment (e.g. git SHA1, dirty bit, build number)
Security version (SVN) to provide Anti-Rollback protection during firmware update

Version Information data structure (BootlLoaderVersionGuid.h):

typedef struct {
  UINT16             BuildNumber;        /* A hour-granularity time stamp     */
  UINT8              ProjMinorVersion;   /* Project or platform major version */
  UINT8              ProjMajorVersion;   /* Project or platform minor version */
  UINT8              CoreMinorVersion;   /* Core code major version           */
  UINT8              CoreMajorVersion;   /* Core code minor version           */
  UINT8              SecureVerNum;       /* Security version number (SVN)     */
  UINT8              Reserved : 5;
  UINT8              BldDebug : 1;       /* Bootloader debug build if 1       */
  UINT8              FspDebug : 1;       /* FSP debug build if 1              */
  UINT8              Dirty    : 1;       /* Dirty flag from git               */
} IMAGE_BUILD_INFO;

typedef struct {
  UINT32             Signature;          /* '$SBH'                            */
  UINT16             HeaderLength;
  UINT8              HeaderRevision;
  UINT8              Reserved;
  UINT64             ImageId;            /* Unique ASCII string per platform */
  IMAGE_BUILD_INFO   ImageVersion;
  UINT64             SourceVersion;      /* First 8 bytes of git SHA1        */
} BOOT_LOADER_VERSION;

Image build data IMAGE_BUILD_INFO can be configured in board configuration file BoardConfig.py. One can specify BUILD_NUMBER in environment variables to provide references in an automated build and release setup (e.g. Jenkins)

During build process, version data is generated and embedded in SBL image with signature $SBH.

During boot, SBL passes version data to OS via HOB data list with GUID gBootLoaderVersionGuid and also prints it to the serial console. For example:

SBID: SB_APLI
ISVN: 001
IVER: 000.005.001.000.02490
SVER: 77F65EAF257FD5DE-dirty
FDBG: BLD(D) FSP(R)
FSPV: ID($APLFSP$) REV(01040301)

For build reproducibility required by certain strict development process, one can provide a hard-coded version information in a file during the build process. See Build Tool for more details.