Hi,
I have downloaded latest GCC and Binutils sources from FSF for M32C
port. Using these sources, I could successfully build the cross
toolchain i.e. m32c-elf-*.
I have observed the following behavior while building an application,
Case 1 - Initialized global variables are not present in the application.
(data section is empty). If I specify the locations of data
section and bss section in the linker script in the
following manner and build the application,
.data 0x00000400 :
{
_data = .;
*(.data)
*(.data.*)
_edata = .;
}
.bss :
{
_bss = .;
*(.bss)
*(COMMON)
_ebss = .;
_end = .;
}
the bss section is located at the location 0x000000 instead
of 0x000400. The value of the variable "_bss" is 0x000000.
The value of the variables "_ebss" and "_end" is 0x000000.
This can be verified from the map file.
In this case the location counter is not incremented
properly. In case of H8 and SH tool chains, the bss section
follows the data section correctly.
Case 2 - One initialized global variable is present in the application
(E.g. int i = 1;).
If I build the application with the above mentioned linker
script, the bss section is located at 0x000402.
The value of the variable "_bss" is 0x000402.
The value of the variables "_ebss" and "_end" is 0x000402.
This can be verified from the map file.
Thus, for the proper follow-up of the bss section (i.e. to
increment the location counter correctly), the data section
should not be empty. Is this behavior expected?
Case 3 - No initialized global variable is present in the application
(data section is empty) but following linker script is used,
MEMORY
{
ram (rw) : o = 0x0000400, l = 31k
rom (rx) : o = 0x000E000, l = 256k
}
.data 0x00000400 :
{
_data = .;
*(.data)
*(.data.*)
_edata = .;
} > ram
.bss :
{
_bss = .;
*(.bss)
*(COMMON)
_ebss = .;
_end = .;
} > ram
In this case the bss section follows the data section
correctly i.e. bss section is located at address 0x000400
and not 0x000000 (as in case 1).
In this case the location counter is incremented correctly.
The above behavior is observed for all m32c targets, i.e. r8c, m16c,
m32c and m32cm.
Is this behavior expected?
Linker script similar to the script specified in case 1, works properly
with H8 and SH tool chains (modified according to their memory maps).
Why does it not work with M32C tool chain?
Do I need to use "MEMORY" command in the linker script as in case 3.
Thanks in advance.
Regards,
Ina Pandit
KPIT Cummins InfoSystems Ltd.
Pune, India
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