This is the mail archive of the
gdb@sources.redhat.com
mailing list for the GDB project.
Re: relocation of shared libs not based at 0
- From: Kevin Buettner <kevinb at redhat dot com>
- To: "Kris Warkentin" <kewarken at qnx dot com>, "Paul Koning" <pkoning at equallogic dot com>, <kevinb at redhat dot com>
- Cc: <gdb at sources dot redhat dot com>, "Peter van der Veen" <peterv at qnx dot com>, "Colin Burgess" <cburgess at qnx dot com>
- Date: Wed, 8 Jan 2003 15:24:36 -0700
- Subject: Re: relocation of shared libs not based at 0
- References: <032c01c2a60a$2368a6e0$0202040a@catdog> <1021218002802.ZM4459@localhost.localdomain> <15871.50596.942339.277490@pkoning.akdesign.com> <08ab01c2b760$2e6612a0$0202040a@catdog>
On Jan 8, 4:52pm, Kris Warkentin wrote:
> This works fine on QNX and (I assume) NetBSD so it looks rather like we just
> have a difference of opinion on how the shared object loader should fill
> things in. We wanted to keep our linker's behaviour for some future
> enhancements (pre-relocating shared objects on flash memory, etc.) so I was
> hoping the fix below (Paul's code with some extra comments) might be
> acceptable. That way Paul and I could just define LM_ADDR_IS_NOT_LOAD_BASE
> in our tm-<host>.h and we'd be off to the races.
>
> static void
> svr4_relocate_section_addresses (struct so_list *so,
> struct section_table *sec)
> {
> #if LM_ADDR_IS_NOT_LOAD_BASE
> /* On some platforms, (ie. QNX, NetBSD) LM_ADDR is the assigned
> address, not the offset.
> The addresses are formed as follows:
> LM_ADDR is the target address where the shared library file
> is mapped, so the actual section start address is LM_ADDR plus
> the section offset within the shared library file. The end
> address is that plus the section length. Note that we pay no
> attention to the section start address as recorded in the
> library header.
> */
> sec->endaddr = svr4_truncate_ptr (sec->endaddr - sec->addr +
> sec->the_bfd_section->filepos +
> LM_ADDR (so));
> sec->addr = svr4_truncate_ptr (sec->the_bfd_section->filepos +
> LM_ADDR (so));
> #else
> sec->addr = svr4_truncate_ptr (sec->addr + LM_ADDR (so));
> sec->endaddr = svr4_truncate_ptr (sec->endaddr + LM_ADDR (so));
> #endif
> }
The problem that I have with the above is that it's not possible to
build a cross debugger that'll have shared library support for both
Linux and NetBSD.
If we could somehow detect (perhaps via the osabi mechanism) that we
have one of the lm-addr-is-not-load-base platforms and enable that
code at runtime, I wouldn't mind...
Kevin