diff options
Diffstat (limited to 'cmd/sbc_harness/static/Documentation/harness_flash_bin.txt')
| -rw-r--r-- | cmd/sbc_harness/static/Documentation/harness_flash_bin.txt | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/cmd/sbc_harness/static/Documentation/harness_flash_bin.txt b/cmd/sbc_harness/static/Documentation/harness_flash_bin.txt index 115f2ee..1b58d6d 100644 --- a/cmd/sbc_harness/static/Documentation/harness_flash_bin.txt +++ b/cmd/sbc_harness/static/Documentation/harness_flash_bin.txt @@ -2,14 +2,20 @@ NAME /harness/flash.bin DESCRIPTION - Access to the flash storage chip (where the harness firmware - is stored). + Access the flash storage chip (where the harness firmware is + stored). - Any number of readers may read the flash contents. + Reading from the file reads the raw flash contents. - Only one writer can have the file open at a time; once the + Writing to the file does not accept raw data; instead the data + must be encapsulated in the [Intel Hex] format, with the Hex + file writing to the region 0x1000_0000-0x1010_0000. While less + convenient than verbatim data, the Hex format provides in-band + checksums and EOF-markers that help prevent rendering the + harness unbootable with corrupted or truncated writes. Any + holes in the Intel Hex file are filled with "1" bits. Once a + complete Intel Hex file has been written without error and 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 @@ -21,13 +27,17 @@ BUGS 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 + chip capacity is usable (the size of the region specified + above is half the chip size); 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. +SEE ALSO: + [Intel Hex]: https://archive.org/details/IntelHEXStandard + AUTHOR Copyright (C) 2025 Luke T. Shumaker <lukeshu@lukeshu.com> SPDX-License-Identifier: AGPL-3.0-or-later |