The rt-loader currently only supports booting piggy backed lzma
compressed kernels. This requires a data layout where the kernel
directly follows the loader. That might not be sufficient for
more complex flash layouts.
Especially bootbase devices (like ZyXEL GS1920) will need some
kind of chain loading that needs to be explored yet.
Enhance the rt-loader as follows:
- Allow to build as standalone version
- In this case a flash start address is given
- During boot loader will search the ROM starting from that address
- If it finds a uImage this will be loaded into RAM
- Afterwards it will be decompressed to its load address
- While we are here add uncompressed uImage support
As always the implementation tries to be as simple as possible.
- uImage detection works without magics
- uImage will be loaded to highest possible memory address
- Documentation in Makefile has been adapted accordingly
Funny side fact: A standalone rt-loader can chain load a piggy
backed rt-loader from flash.
During bootup loader will show
rt-loader
Running on RTL8380M (chip id 6275C) with 256MB
Relocate 15760 bytes from 0x82000000 to 0x8ffa0000
Searching for uImage starting at 0xb45a0000 ...
uImage 'MIPS OpenWrt Linux-6.12.40' found at 0xb45a0000 with load address 0x80100000
Copy 2923034 bytes of image data to 0x8fcd61e6 ...
Extract image with 2923034 bytes from 0x8fcd61e6 to 0x80100000 ...
Final kernel size is 2923034 bytes
Booting kernel from 0x80100000 ...
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/19832
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Provide a crc32 function (will be needed later). Do some
minor naming and coding cleanups
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/19832
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
The RTL931x devices have an other register that describes the
current RAM configuration. Enhance the identification routine.
Tested on LGS352C (RTL9311).
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/19284
Signed-off-by: Robert Marko <robimarko@gmail.com>
Until now the rt-loader only works on U-Boot driven devices where the
environment (e.g. coprocessor) is usually setup properly. Devices like
the ZyXEL GS1920 series use BootBase as start environment and skip
some of the basic initialization steps. rt-loader will fail in these
cases. Take care about the CP0 registers.
Additionally enhance the documentation of the printf implementation.
It was optimized during the different revisions of the initial PR.
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/19253
Signed-off-by: Robert Marko <robimarko@gmail.com>
The bootloader of many Realtek switches only supports gzipped kernel images.
With limited flash space that might get critical in future versions. For better
compression allow support for compressed images. For this a new loader was
developed. Several ideas have been taken over from the existing lzma loader
but this has been enhanced to make integration simpler. What is new:
- Loader is position independent. No need to define load addresses
- Loader identifies device memory on its own
- Loader uses "official" upstream kernel lzma uncompress
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/lib/decompress_unlzma.c
- Loader uses "official" UNMODIFIED nanoprintg that is used by several
bare metal projects. https://github.com/charlesnicholson/nanoprintf
Compiled the loader ist just under 12KiB and during boot it will show:
rt-loader
Found RTL8380M (chip id 6275C) with 256MB
Relocate 2924240 bytes from 0x80100000 to 0x8fce0000
Extract kernel with 2900144 bytes from 0x8fce521c to 0x80100000...
Extracted kernel size is 9814907 bytes
Booting kernel from 0x80100000 ...
[ 0.000000] Linux version 6.12.33 ...
[ 0.000000] RTL838X model is 83806800
...
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/18397
Signed-off-by: Robert Marko <robimarko@gmail.com>
