Learn more about implementing a UEFI BIOS into an Embedded System with this informative presentation from Insyde Software's Charles Marslett

1. Implementing a UEFI BIOS
in an Embedded System
Insyde Software
© 2013 Insyde Software
1

2. Insyde Software
• Develops, deploys and supports the latest BIOS
replacement firmware that is based on the UEFI
Framework and UEFI 2.x
• Embedded BIOS business
– Many of Intel’s largest embedded customers continue adoption of
InsydeH2O across multiple business units
• Strong alignment to Intel ECG Roadmap and platforms
• Founded September 1998
© 2013 Insyde Software
2

3. Agenda
• Understanding the UEFI architecture
• The role of a UEFI BIOS in an x86 embedded
design
• Where to get support when you need it
© 2013 Insyde Software
3

4. Key Benefits of UEFI Firmware
 Provides industry standard interfaces
for CPUs, chipsets and platform features
 Modular source code base can be used
across different products
Compatibility
Support Module
Insyde
Drivers
 Adapted by Intel, AMD, Microsoft
OEM /ODM
Drivers
 Easier to implement new technologies
and features
Generic
Drivers
 Pre-boot environment facilitates innovation
Legacy
UEFI
UEFI
Pre-boot Option OpRom
Tools
ROMs and
Legacy
OS
UEFI API
UEFIenabled
OS
Foundations
Architectural Protocols
Hardware
© 2013 Insyde Software
4

5. Boot Flow
© 2013 Insyde Software
5

6. Security Phase (SEC)
• When the processor’s RESET line is released and the first
instruction is fetched from the RESET vector, the SEC
phase begins
• Objectives:
– The first part of the SEC is a small assembly language
module that switches the processor from 16-bit real
mode to 32-bit protected mode
– Next, it enables a memory model that permits stack
based C code to be executed with only a few
limitations
– The SEC is the security kernel, it can also authenticate the
next phase’s code verifying it to be trustworthy
© 2013 Insyde Software
6

7. Security Phase
SEC
1. SEC creates an early
cache based memory
environment
2. SEC knows the fixed
location of the boot
firmware volume and
can validate the PEI
image
3. SEC passes control
to PEI core located
in the BFV
Trustworthy
RAM
Boot
Firmware
Volume
PEI Core
PEIMS
© 2013 Insyde Software
7

8. Pre-EFI Initialization (PEI)
• The PEI phase is responsible for initializing enough of the
system to provide a stable base for the remainder of the BIOS
• PEI phase handles detecting and recovering from corruption
and failure of the firmware store
• PEI phase consists of three stages:
– The smallest possible set of modules to prepare for the
initialization of the memory (critical bus and processor
configuration)
– Memory initialization & capture of information to be passed to
the OS and the remainder of the BIOS
– Checking for firmware corruption and setting the boot mode to
address special cases if necessary
© 2013 Insyde Software
8

9. Handoff Blocks (HOBs)
• A Handoff Block (HOB) is a binary data structure that
contains information to be passed from a PEI Module
to a DXE driver, application or OS component
• HOBs are the standard way information is passed
from the PEI Phase to later phases of the BIOS
© 2013 Insyde Software
9

10. The Driver Execution (DXE) Phase
• The DXE phase is that part of the code where most of
the system initialization is performed
– It is loaded and executed once the PEI phase has
finished initializing system memory for the platform.
• Its function is to:
– Do all the remaining necessary hardware setup and set up
the UEFI System Table structures to provide the necessary
services to the Boot Device Selection (BDS) code for it to
run transient applications and OS loaders
– Provide the API interfaces needed by OS loaders to boot
all the supported OSes
© 2013 Insyde Software
10

11. Components of the DXE Phase
• DXE Core
– Main DXE executable binary; creates tables identifying Boot and Runtime
Services; responsible for dispatching drivers and setting up the DXE tables
• DXE Drivers
– A module loaded by the Core to perform initialization and/or to produce
protocols and other services
• DXE Dispatcher
– Part of the DXE Core: searches for and executes drivers
• DXE Architecture Protocols
– Produced by DXE drivers; to abstract DXE from hardware
• EFI System Table
– Contains pointers to UEFI service tables, configuration
data, thehandle database and console devices
© 2013 Insyde Software
11

12. The UEFI System Table
Active Consoles
Input Console
Output Console
Standard Error Console
EFI
System
Table
EFI Runtime Services Table
Variable Services
Real-Time Clock Services
Reset Services
Status Code Services
EFI Boot Services Table
Virtual Memory Services
Task Priority Level Services
Memory Services
Version Information
Event and Timer Services
EFI Specification Version
Protocol Handler Services
Firmware Vendor
Image Services
Firmware Revision
Driver Support Services
DXE Services Table
Global Coherency Domain Services
Dispatcher Services
System Configuration Table
DXE Services Table
HOB List
ACPI Table
SMBIOS Table
Handle Database
Protocol Interface
Protocol Interface
Protocol Interface
Protocol Interface
Protocol Interface
Protocol Interface
Boot Services and Structures
Only available before the OS runtime
…
SAL System Table
Runtime Services and Structures
Available before and during OS runtime
© 2013 Insyde Software
12

13. The Handle Database
The Handle Database
Each Handle
GUID Interface
The DXE Driver Image
GUID Interface
...
...
BlkIo->ReadBlocks(BlkIo, …)
Protocol Interface
Function Pointer
Function Pointer
...
Device-Specific
Context
© 2013 Insyde Software
13

14. Dispatching the BDS Protocol Entry()
• The DXE dispatcher exits when it can not find and
dispatch any more drivers
• It invokes the BDS Protocol Entry() service
• should the Entry() service return, the dispatcher makes
another pass to find any additional drivers now able to
execute and dispatches them, then executes the Entry()
service again
DXE
Core
DXE Phase foundation
completed
DXE
Dispatcher
Completed
dispatching DXE
drivers
BDS.Entry
State changed, attempt to
load additional DXE drivers
© 2013 Insyde Software
14

15. Agenda
•
Understanding the UEFI architecture
•
The role of a UEFI BIOS in an x86
embedded design
•
Where to get support when you need it
© 2013 Insyde Software
15

16. UEFI Advantages
• Embedded system often have unique hardware and a
UEFI BIOS isolates pre-boot applications and OS
initialization code from the hardware
• The code is based on effective standards and UEFI BIOS
uses widely available development environments to
reduce training and learning curve demands
• Since UEFI drivers are written in C and a UEFI BIOS has a
consistent driver architecture and simple dispatchers, a
driver writer can be productive almost immediately
• Using portable coding methods, InsydeH2O is also an
example of how common UEFI BIOS code can support
32- and 64-bit x86, ARM and Itanium platforms
© 2013 Insyde Software
16

17. Starting a new Huron River based Project
PROJECT_FAMILY
PROJECT_NAME
= ProjectInsyde
= $(DEMOBOARD_NAME)
PROJECT_FAMILY
PROJECT_NAME
= ProjectSeussCorp
= Thing1
2. Edit BuildPlatform.env to point to the
new directory
3. Build a clone of the Huron River CRB
BIOS to check your work
1. Copy the ProjectInsydeHuronRiver
directory to ProjectSeussCorpThing1
© 2013 Insyde Software
17

18. Adapt the Project Directory to your
Hardware
•
•
•
•
•
•
•
•
•
Change clock generator code if necessary
Change interrupt routing if necessary
Change Smbus MUX code or remove it, as needed
Change SPD addresses if needed
Change Insyde feature set choices to match your
requirements (if you are starting from an Insyde BIOS)
Do a test build: if it is successful, you may have an easy
porting effort
Comment out everything that should not be required for
a first “bring up” build
Build your “bring up” BIOS and test it on the new
hardware
Add commented out features, one at a time
© 2013 Insyde Software
18

19. Add New Drivers and Feature Support Code
• Here you have to write new code; or you may need
to port code from a previous PPC, ARM or legacy
BIOS
• Some of the new code will be inserted into existing
drivers and PEIMs, some of it will form entirely new
drivers and PEIMs
• These changes often involve the user interface, and
they should be carefully specified so as to minimize
the need to redesign after building the first
prototype
© 2013 Insyde Software
19

20. Agenda
•
Understanding the UEFI architecture
•
The role of a UEFI BIOS in an x86 embedded
design
•
Where to get support when you need it
© 2013 Insyde Software
20

21. Don’t Forget Support!
• Insyde Support
•
•
•
•
•
•
•
Engineer to engineer support
Experienced firmware engineers
Worldwide training and certification
Turn key support or support as needed
Worldwide support
Strong Intel partnership
Ready to help – Now!
© 2013 Insyde Software
21

22. Thank You!
© 2013 Insyde Software
22

23. Insyde Software is an Affiliate member of the Intel® Intelligent Systems Alliance, a
global ecosystem of 200+ member companies that provide the performance,
connectivity, manageability, and security developers need to create smart, connected
systems
Insyde and InsydeH2O are registered trademarks of Insyde Software.
Intel is a registered trademark of Intel Corporation in the United States and other countries.
© 2013 Insyde Software
23