question about 'r2' !!!

Hi, all,
As everyone konws, Linux use register 'r2' as a reference of 'current',which
is realized by
GCC. Also, the exeception handling of Linux do some work about 'r2'.

I am currently engaged in compiling Linux-ppc source tree using a CC other
than GCC.
The CC can only produce the executable format of 'EABI', a convention made
by Motorola.
And 'EABI' use 'r2' as a base address register for reference of const data,
which can't
be changed. So I want to use a general global varialbe as 'current', leaving
'r2' to 'EABI'.

Anyone has some experence in such issue?
what consideration I must take?
I am pleased to get any comments from you .
Thanks a lot

Rolf


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