Motorola ATCA-717 - Manual (Page 113)

Flash Devices Devices’ Features and Data Paths
PENT/ATCA−717 113
Flash Devices
The blade provides two redundant boot flash devices: one default boot flash and one
backup boot flash. During blade production, both flashes are programmed with identical
BIOS images. The presence of two redundant flash devices allows for remotely updating
BIOS images from the operating level without interrupting running processes and
without being affected by possibly corrupt BIOS images. The backup boot flash,
furthermore, can be used to store customized images. Note that in this case the redundant
BIOS feature is no longer available.
a
Both flash devices are Intel−compatible firmware hubs that are connected to the LPC
interface of the South Bridge. Each flash device has a unique four bit LPC device ID. Bit 1
to 3 of the device ID are fixed to 0. Bit 0 is controlled by a boot flash select signal provided
by the IPMC in such a way that bit 0 of one flash is set to 0 while bit 0 of the other flash is
set to 1 and vice versa. The following figure shows the implementation on
hardware−level.
a
Default Boot
Flash
Backup Boot
Flash
IPMC
ID0
ID1
ID2
ID3
ID0
ID1
ID2
ID3
Boot Flash
Select Signal
Figure 35: Boot Flash LPC Device ID Control
The blade’ s CPU always boots from the boot flash with the LPC device ID 0. Thus the
boot flash select signal of the IPMC allows to select the flash device that the CPU is to
boot from.
a
An IPMI Set System Boot Options command allows to control the boot flash select signal
and thus select between the default and backup boot flash as device to boot from. For
details refer to the
a PENT/ATCA−715/717/7105/7107: Control via IPMI Programmer’s Guide a
which can be downloaded from the former Force Computers S.M.A.R.T. server or the
Motorola literature catalog.
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By default, the data/instruction areas of the default and backup boot flash are writable.
This is necessary because during booting the BIOS writes some configuration data back to