Re: [ECOS] .previous -- directive

["Michael Anburaj" <embeddedeng at hotmail dot com>]

Hi Billy,


Thanks a lot for the links, now I am clear on those 2.

Excuse me for the lengthy email.
I am tying to understand the .ecos.table.devtab.

My understanding:
-----------------------
1. The ?DEVTAB_ENTRY(some_lable_name,...)? should append data structures in 
the .ecos.table.devtab.data SUB-SECTION
2. I guess the ?CYG_HAL_TABLE_BEGIN( __DEVTAB__, devtab )? & 
?CYG_HAL_TABLE_END( __DEVTAB_END__, devtab )?, should place these objects 
?__DEVTAB__ <.ecos.table.devtab.begin >? & ?__DEVTAB_END__ 
<.ecos.table.devtab.finish >? above & below .ecos.table.devtab.data 
SUB-SECTION (for simpicity sake: forget the .extra may be other 
sub-sections). Am I right? If so, How does this get arranged in this manner?
a. why should .ecos.table.devtab.begin get placed before 
.ecos.table.devtab.data
b. And why should .ecos.table.devtab.finish get placed after 
.ecos.table.devtab.data


I tied a simple experiment (outside the ecos frame-work):

Linker scipt:
------------
Has 2 SECTIONS

.text
{
with subsection, but did not explicitly specify any subsection for 
.ecos.table.devtab.*
}

.data
{
}


When I looked at the output map file:
-------------------------------------

.ecos.table.devtab.begin
               0x0000000080102c04        0x0

.ecos.table.devtab.finish
               0x0000000080102c04        0x0

.ecos.table.devtab.data
               0x0000000080102c04       0x24
.ecos.table.devtab.data
               0x0000000080102c04       0x24 dds.o
               0x0000000080102c1c                atlas_struct2
               0x0000000080102c04                atlas_struct0
               0x0000000080102c10                atlas_struct1


This was the reason both __DEVTAB__ & __DEVTAB_END__ read the same address 
(0x80102c04) in my test program.

Well, I could explicitly define subsection ?.ecos.table.devtab.data? in my 
linker script & added name_objects about & below this to get the ABSOULE(.) 
address of start & end. But I really want to understand how it works in 
ecos.

The only difference I found was in the ecos?s .ld files (mips_mips32.ld) 
?KEEP(*( SORT (.ecos.table.*))) ;?. Is the line responsible for this magic 
(placing the .ecos.table.devtab.begin about .ecos.table.devtab.data & 
.ecos.table.devtab.finish below .ecos.table.devtab.data)? Or some else?

Thanks a lot,
-Mike.

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