Status of ARM BE8 support?

Asked by Thomas Garcia

It seems that gcc-arm does include the byte_order_for_code patches but BE8 support still seems all sorts of broken. Here's my experience:

+ gdb ``load``-ing a program seems to work (i.e. load the program in correct order) no matter what the gdb endian mode is. I'm guessing that this is because it's using the endianness of the executable. The PC is also set correctly regardless of gdb's endian mode.

+ Reading and writing memory is always either Big endian or Little endian. IOW it doesn't change based on the portion of memory you're reading as you might expect. For example, reading instruction space in big endian mode reads the instructions byte-reversed, and reading data in little endian mode reads the data byte-reversed. I'm guessing this is because this type of support simply doesn't exist for gdb. Is that right?

So, things being the way they are currently, gdb simply doesn't work for BE8 if you're trying to do anything more than load a program to the core.

Getting to my actual questions...

1. There is an additional BE8 patch set that was submitted about a year ago to gdb (see [1] for patch submission). Part of this seems to address the issue of reading instructions correctly but I have been unable to test. Are these going to be added to gcc-arm eventually?

https://sourceware.org/ml/gdb-patches/2014-10/msg00526.html

2. Is there anything in the works or even any interest in getting more complete BE8 support in gcc-arm? (Specifically, being able to automatically "know" what endianness to use for a particular region of memory.).

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