Re: [ECOS] i386/Windows target?

[Bart Veer <bartv at redhat dot com>]

>>>>> "Tom" == Tom M Yeh <tomyeh@infoshock.com> writes:

    Tom> Thanks for your information. However, I wonder why eCos
    Tom> demands ELF. Can we use the native compiler for Cygwin
    Tom> (i686-pc-cygwin-*)? Don't the PowerPC version use another
    Tom> format?

The configure triplet for powerpc specifies eabi, but this is just ELF
with some minor additions/tweaks/clarifications.

eCos does not specifically demand ELF, in that there is nothing in the
source code which knows about ELF executables. However it does require
the following:

1) constructor priority ordering. This is most easily implemented by
   putting the static objects into appropriately numbered linker
   sections, and sorting them in the linker script. So you need an
   image format which supports lots of linker sections.

2) linker garbage collection, also known as selective linking. This is
   most easily implemented by putting every function and variable into
   its own linker section. Strictly speaking this is not absolutely
   necessary, but without it the final executables will be
   significantly bigger than necessary. Arguably this is not so much
   of a problem when using a synthetic target.

3) weak symbol support.

ELF can handle all of this. Older image formats typically cannot, e.g.
there are likely to be strict limits on the number of linker sections
you can create. I do not know exactly what the limitations are in the
image format currently used by Windows, so I cannot comment further.

Bart Veer // eCos net maintainer