Comtrol eCos - Manual (Page 109)

Chapter 1. Getting Started with RedBoot
To save flash resources, use a ROMRAM mode RedBoot, or if using a ROM mode RedBoot, avoid reserving space
for the RedBoot[RAM] image (this is done by changing the RedBoot configuration) and download the RAM mode
RedBoot whenever it is needed. If the RedBoot image takes up a fraction of an extra flash block, it may be possible
to reduce the image size enough to free this block by removing some features.
RAM Resources
RedBoot reserves RAM space for its run-time data, and such things as CPU exception/interrupt tables. It normally
does so at the bottom of the memory map. It may also reserve space at the top of the memory map for configurable
RedBoot features such as the net stack and zlib decompression support.
To see the actual amount of reserved space, issue the version command, which prints the RedBoot banner, including
the RAM usage:
RedBoot> version
RedBoot(tm) bootstrap and debug environment [ROM]
Non-certified release, version UNKNOWN - built 13:31:57, May 17 2002
Platform: FooBar (SH 7615)
Copyright (C) 2000, 2001, 2002, Red Hat, Inc.
RAM: 0x06000000-0x06080000, 0x06012498-0x06061000 available
FLASH: 0x00000000 - 0x00080000, 8 blocks of 0x00010000 bytes each.
To simplify operations that temporarily need data in free memory, the limits of free RAM are also available as
aliases (aligned to the nearest kilo-byte limit). These are named FREEMEMLO and FREEMEMHI, and can be
used in commands like any user defined alias:
RedBoot> load -r -b %{FREEMEMLO} file
Raw file loaded 0x06012800-0x06013e53, assumed entry at 0x06012800
RedBoot> x -b %{FREEMEMHI}
06061000: 86 F5 EB D8 3D 11 51 F2 96 F4 B2 DC 76 76 8F 77 |....=.Q.....vv.w|
06061010: E6 55 DD DB F3 75 5D 15 E0 F3 FC D9 C8 73 1D DA |.U...u]......s..|
To reduce RedBoot’s RAM resource usage, use a ROM mode RedBoot. The RedBoot features that use most RAM
are the net stack, the flash support and the gunzip support. These, and other features, can be disabled to reduce the
RAM footprint, but obviously at the cost of lost functionality.
Configuring the RedBoot Environment
Once installed, RedBoot will operate fairly generically. However, there are some features that can be configured
for a particular installation. These depend primarily on whether flash and/or networking support are available. The
remainder of this discussion assumes that support for both of these options is included in RedBoot.
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