* Global Offset Table question..
@ 2001-09-22 20:42 Dave Airlie
2001-09-22 21:29 ` [LV] " Dave Airlie
2001-09-22 22:01 ` Brian Gerst
0 siblings, 2 replies; 3+ messages in thread
From: Dave Airlie @ 2001-09-22 20:42 UTC (permalink / raw)
To: linux-kernel, linux-vax
I've been trying to get dynamic loading on the Linux/VAX project going,
and I've having trouble with the Global Offset Table and how it magically
gets in to the ebx register on x86.. where is this done?
I think I've looked at the kernel, gcc, binutils, ld.so 1.9, glibc 2.2.3
and can't see exactly where this happens...
Anyone care to enlighten my poor brain...
Thanks,
Dave.
--
David Airlie, Software Engineer
http://www.skynet.ie/~airlied / airlied@skynet.ie
pam_smb / Linux DecStation / Linux VAX / ILUG person
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [LV] Global Offset Table question..
2001-09-22 20:42 Global Offset Table question Dave Airlie
@ 2001-09-22 21:29 ` Dave Airlie
2001-09-22 22:01 ` Brian Gerst
1 sibling, 0 replies; 3+ messages in thread
From: Dave Airlie @ 2001-09-22 21:29 UTC (permalink / raw)
To: linux-vax; +Cc: linux-kernel
okay would I be in the right place if I was looking in gcc at
PIC_OFFSET_TABLE_REGNUM
Dave. dazed agus confused.
On Sat, 22 Sep 2001, Dave Airlie wrote:
>
> I've been trying to get dynamic loading on the Linux/VAX project going,
> and I've having trouble with the Global Offset Table and how it magically
> gets in to the ebx register on x86.. where is this done?
>
> I think I've looked at the kernel, gcc, binutils, ld.so 1.9, glibc 2.2.3
> and can't see exactly where this happens...
>
> Anyone care to enlighten my poor brain...
>
> Thanks,
> Dave.
>
>
--
David Airlie, Software Engineer
http://www.skynet.ie/~airlied / airlied@skynet.ie
pam_smb / Linux DecStation / Linux VAX / ILUG person
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Global Offset Table question..
2001-09-22 20:42 Global Offset Table question Dave Airlie
2001-09-22 21:29 ` [LV] " Dave Airlie
@ 2001-09-22 22:01 ` Brian Gerst
1 sibling, 0 replies; 3+ messages in thread
From: Brian Gerst @ 2001-09-22 22:01 UTC (permalink / raw)
To: Dave Airlie; +Cc: linux-kernel, linux-vax
Dave Airlie wrote:
>
> I've been trying to get dynamic loading on the Linux/VAX project going,
> and I've having trouble with the Global Offset Table and how it magically
> gets in to the ebx register on x86.. where is this done?
>
> I think I've looked at the kernel, gcc, binutils, ld.so 1.9, glibc 2.2.3
> and can't see exactly where this happens...
>
> Anyone care to enlighten my poor brain...
>
> Thanks,
> Dave.
>
I assume you are talking about position independant code? On the x86,
the only instructions that can use IP-relative addressing are branch
instructions. This asm fragment shows how it's done:
call 1f
1: popl %ebx
addl $(GOT - 1b), %ebx
If the Vax has better support for IP-relative addressing, this may be
easier. On recent x86 procesors, the above code will screw up the
call/return cache (branch prediction) and cause performance penalties.
--
Brian Gerst
^ permalink raw reply [flat|nested] 3+ messages in thread
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