RE: [avr-libc-dev] [RFC] Unified ELF file

[Eric Weddington]

> -----Original Message-----
> From: Colin O'Flynn [mailto:address@hidden
> Sent: Tuesday, October 02, 2007 8:41 PM
> To: address@hidden
> Cc: Eric Weddington
> Subject: Re: [avr-libc-dev] [RFC] Unified ELF file
>
> But the patches did work for me OK, example built. I'm not
> really sure of
> this: but should there be more flags for the .fuse section?
>
> Right now I see this from "avr-objdump -x test.elf"
>
>   0 .text         00000a3e  00000000  00000000  00000094  2**1
>                   CONTENTS, ALLOC, LOAD, READONLY, CODE
>   1 .eeprom       00000028  00810000  00810000  00000ad2  2**0
>                   CONTENTS, ALLOC, LOAD, DATA
>   2 .fuse         00000003  00820000  00820000  00000afa  2**0
>                   ALLOC
>   3 .stab         00000a5c  00000000  00000000  00000afc  2**2
>                   CONTENTS, READONLY, DEBUGGING
>   ....more stuff i don't care about, and note I added EEPROM
> to see what that
> section has set....
>
> Shouldn't we have the CONTENTS and READONLY flag as well? I
> don't know why the
> READONLY flag should be set, just that it is set in
> everything else ;-)

In practice, I don't think it really much matters, as it will external tools
that will handle that section anyway, and those tools don't really care what
the flags are set to; only that the data is correct.

But, in theory, I think that .fuse should not have ALLOC (does the OS need
to allocate memory when loading the file?). I think that .fuse should not
have READONLY (can't we read the fuses from the device and write to an ELF
file? Should it even have LOAD (the fuse data is not technically a part of
the application)? I don't think that DATA qualifies either, as this is not
data that the application uses directly.

When a __fusemem__ attribute gets added to GCC, then (I think) we should be
able to set the flags as needed. From looking at the ld manual, I don't see
how to do it with just linker script machinery.

Eric