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Diffstat (limited to 'cmd/sbc_harness/static/Documentation/harness_flash_bin.txt')
| -rw-r--r-- | cmd/sbc_harness/static/Documentation/harness_flash_bin.txt | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/cmd/sbc_harness/static/Documentation/harness_flash_bin.txt b/cmd/sbc_harness/static/Documentation/harness_flash_bin.txt new file mode 100644 index 0000000..115f2ee --- /dev/null +++ b/cmd/sbc_harness/static/Documentation/harness_flash_bin.txt @@ -0,0 +1,33 @@ +NAME + /harness/flash.bin + +DESCRIPTION + Access to the flash storage chip (where the harness firmware + is stored). + + Any number of readers may read the flash contents. + + Only one writer can have the file open at a time; once the + file is closed, the harness reboots into the new firmware. + Writes to the top half of the chip will fail. + +BUGS + - The size of the chip is configured at compile-time. If the + firmware is loaded onto hardware with a larger flash chip + than it was compiled for, then the upper part of the chip + will not be accessible with this file. If the firmware is + loaded onto hardware with a smaller flash chip than it was + compiled for, then accessing the missing upper part of the + chip will crash. + + - When writing to the flash using this file, only half of the + chip capacity is usable; the top half and bottom half are + mirrors of each-other. This is to avoid the firmware + crashing as its program text is overwritten; the firmware is + executing out of the bottom half, and writing to the top + half; once the file is closed, a minimal in-RAM function + copies the top half to the bottom half and reboots. + +AUTHOR + Copyright (C) 2025 Luke T. Shumaker <lukeshu@lukeshu.com> + SPDX-License-Identifier: AGPL-3.0-or-later |