cExpress-BL
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4.6.
BIOS Select and Mode Configuration Switch
The module has two BIOS chips and BIOS operation can be configured to "PICMG" and dual-BIOS "Failsafe" modes using the BIOS Select
and Mode Configuration Switch, Pin 2.
Setting the module to PICMG mode will configure the BIOS chips on the module as SPI0 and SPI1. In PICMG mode, a BIOS chip cannot be
placed in the SPI0 slot on the carrier.
In dual-BIOS Failsafe mode, both BIOS chips on the module are configured as SPI1. Only one of the two is connected to the SPI bus at any
given time. In case of failure of the primary SPI1 BIOS, the system will reboot and switch to the secondary SPI1 BIOS on the module. In
Failsafe mode, the SPI0 BIOS socket on the carrier can be populated.
In either mode, BIOS Select and Mode Configuration Switch, Pin 1 is used to select whether to boot from SPI0 or SPI1.
Mode
Pin 1
Pin 2
Boot from SPI0 (default)
On
—
Boot from SPI1
Off
—
Set BIOS to PICMG mode
—
On
Set BIOS to Failsafe BIOS mode (default)
—
Off
BIOS Select and Mode
Configuration Switch
