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Regarding eCos startup
- From: "Dileep Kumar" <dileepkumart at gmail dot com>
- To: ecos-discuss at sourceware dot org, "Gary Thomas" <gary at mlbassoc dot com>, "Wolfgang Denk" <wd at denx dot de>
- Date: Thu, 20 Mar 2008 12:30:47 +0530
- Subject: [ECOS] Regarding eCos startup
Hi,
I am trying to port eCos on MPC8555 processor . MPC8260 is
the baseline I considered .
In MPC8555E processor when a reset occurs , control will go to
location FFFF_FFFC. This particular location always contain a
branch instruction to boot page.
In MPC8260 ecos2.0b1 code control will go to the point
"_exception_reset " and the startup file is "vectors.S" .
( As specified in the linker script file " powerpc.ld ")
This " _exception_reset " comes under " .vectors " section
Well now , my problem is , it is not possible to load " .vectors " section
at address starting from FFFF_FFFC, because this section is
bigger to hold at addresses FFF_FFFC, FFFF_FFFD,FFFF_FFFE and
FFFF_FFFF.
In Uboot code for MPC8555E , there is a separated file
" resetvec.S " ,this contain a single branch instruction to _start( which is
in the file start.S ) . This branch insrtuction is under the section
" .resetvec " . This section can be loaded at FFFF_FFFC , because
it contain only one instruction .
One silution is to use the way what Uboot had done, but we have to change
linker script file (powerpc.ld ). This is not possible ,because it is
under " arch " directory .
Is there any other solution to come out of this ?
Thanks
Dileep Kumar
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