RE: .bss segment alignment

RE: .bss segment alignment

[Bud Davis]

Not to sure if this will help, but you can force a fortran common to a
specific virtual address at link time by passing ld some commands:
 


g77 <usual stuff > -Wl,--defsym -Wl,global01_=0x40200000


with this you know that "COMMON / GLOBAL01 /" will be in a fixed
location.  i have used this in the past to map fortran common to shared
memory using shmat to a fixed address.

you can probably force anything to be anywhere with ld commands, but I
have no clue on the details :)


regards,
bud davis

.bss segment alignment

[Wehrer, Michael J.]

Help,

I am having a problem with an application that calls munmap to unmap memory assigned to a variable in the .bss segment. unmap fails with a status of Invalid argument. I believe the reason for the failure is that the variable is not aligned on a page boundary. 

An objdump of the binar file shows the following information for the variable:

0805a9e0 g O .bss   00001000 vaicom_

The variable in question is created by g77 in a block data program. It is then linked together with gcc modules. 

Is there a way to tell the g77/gcc compiler or linker that this variable must start on a page boundary within the .bss segment? I have tried everthing I can think of. This works on Tru64UNIX with the standard f77/cc compiler but does not work on Red Hat 9.0 for i386.



Sincerely yours,

Mike Wehrer