Products > Embedded Computing

Anyone still using Mikrotik rb532A? (2006, mips32le router)

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DiTBho:
When it appeared in 2006, it was the era of Linux v2.6, v2.6.22 to v2.6.32 were the kernels of greatest interest and support, especially by OpenWRT.
When I write on { NetBSD, Linux/MIPS, ... } ML ... nobody replies. Sounds abandoned platform.

Then came the RPI and other cheaper SBCs, and the rb532a took a back seat until the END of LIFE declared by the manufacturer.

I can boot kernel 6.0x, but there are still many unresolved issues.

First of all, the firmware has some undocumented quirks, sometimes it refuses to tftpboot elf binaries, but it doesn't explain why, nor does it provide an error message that can help.

Second, the firmware refuses to accept some Microdrive, it doesn't explain why, it only says "CF not present", while you hear the motor spinng down.

Third, the firmware requires you partition the NAND flash into two slices.

--- Code: ---dev:    size   erasesize  name
mtd0: 00400000 00020000 "Routerboard NAND boot"
mtd1: 07c00000 00020000 "rootfs"

--- End code ---
The first slice must be 4Mbyte size, and must be "yaffs" formatted. The linux kernel must be renamed "kernel", otherwise it won't load it.

Here the first problem: 4-Mbyte is too small for a modern kernel v6, which is usually not less than 7-Mbyte with the minimal configuration.
Secondly, the "yaffs" (flash-oriented) filesystem was never included in the linux kernel, worse still it is no longer supported since a while.


Anyone still using it?  :-//

DiTBho:
based on IDT-79RC32434.
A few interesting posts about its performance here on the Forum.


edit:
Latest Rooterboot with fixes mentioned specifically for rb532a is v2.18, see changelog

DiTBho:
"kernel out of range" during Tftpboot

This error is not related to the binary dimension of the elf.
I have not yet figured out what it is related to.


--- Code: ---RouterBOOT booter 2.8

RouterBoard 532A

CPU frequency: 399 MHz
  Memory size:  64 MB

Press any key within 2 seconds to enter setup..
trying bootp protocol... OK
transfer started
.......................................................... transfer
ok, time=2.76s
setting up elf image... kernel out of range
kernel loading failed

--- End code ---

Nominal Animal:

--- Quote from: DiTBho on January 21, 2025, 09:35:38 pm ---This error is not related to the binary dimension of the elf.
I have not yet figured out what it is related to.
--- End quote ---
I believe RouterBOOT 2.8 is very limited in what address ranges it can load a kernel at, and the "kernel out of range" error indicates the kernel image wants to be loaded outside that range.  Simply put, it's RouterBOOT 2.8 being stupidly limited/limiting.

(If the kernel image is compressed, then it could also be that RouterBOOT loads the compressed image to the same address range as the kernel wants to be decompressed to.)

I fear your only options are to play with the kernel base address (CONFIG_PHYSICAL_START).  I don't know if RouterBOOT allows changing where it loads the compressed image, what the 4MB range it has reserved for that is.

DiTBho:

--- Quote from: Nominal Animal on January 23, 2025, 12:58:34 am ---I believe RouterBOOT 2.8 is very limited in what address ranges it can load a kernel at, and the "kernel out of range" error indicates the kernel image wants to be loaded outside that range.  Simply put, it's RouterBOOT 2.8 being stupidly limited/limiting.

--- End quote ---

Yup, RouterBoot is full of quirks, and the user manual doesn't say anything.
I emailed severally and several times to Mikrotik, they never answered.

Over time, and by trying it myself, I discovered that it expects

* The first partition of the Microdrive/Compact Flash formatted with PC-partition scheme, the first partition must have part_type=27, contaning no filesystem, and the size must be equal to 8Mbyte, it will "raw load" into ram, and executed.
* The flash must be partitioned with a fixed scheme, and must contain two YaFFs v1 (v2 won't work) partitions. The first partition must be equal to 4Mbyte and must contain a file "kernel"
* Not yet understood if the tftpboot is limited below 8Mbyte, not clear, sometimes it works, sometimes it does not
I could only speculate that RouterBoot opens an 8Mbyte window in the way it addresses RAM for the application.elf (the linux kernel in my case) to load and boot  :-//

Unfortunately these things are not written anywhere, and that ... even in OpenWRT have never been clear.
Patches are confusing, and, worse still, patches don't come with a note in their header.

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