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Re: [PATCH 4/9] [ARC] Don't convert _DYNAMIC@ to _GLOBAL_OFFSET_TABLE_
- From: Cupertino Miranda <Cupertino dot Miranda at synopsys dot com>
- To: Nick Clifton <nickc at redhat dot com>, Cupertino Miranda <Cupertino dot Miranda at synopsys dot com>, "binutils at sourceware dot org" <binutils at sourceware dot org>
- Cc: "Claudiu dot Zissulescu at synopsys dot com" <Claudiu dot Zissulescu at synopsys dot com>, "Francois dot Bedard at synopsys dot com" <Francois dot Bedard at synopsys dot com>, Vineet Gupta <Vineet dot Gupta1 at synopsys dot com>
- Date: Tue, 6 Jun 2017 16:08:50 +0000
- Subject: Re: [PATCH 4/9] [ARC] Don't convert _DYNAMIC@ to _GLOBAL_OFFSET_TABLE_
- Authentication-results: sourceware.org; auth=none
- References: <20170523154056.19234-1-cmiranda@synopsys.com> <20170523154056.19234-5-cmiranda@synopsys.com> <186be8ec-ae9f-6ecd-50d1-1604e0e9b3c2@redhat.com>
Hi Nick,
Yes, there is some sort of incompatibility to legacy code.
However, as far as we know this was a special relocation / assembly
exception only used for uClibc dynamic loader, in order to compute
library relative virtual offset.
This was part of the old tools never upstreamed, and the side effects /
problems created with it were unnoticed by us when we first start
upstreaming.
More recently, I have been involved in porting glibc for ARC and I have
came across this "naughtiness", and suggested to clean it up, for uclibc
and glibc.
Current version of uClibc is no longer relying on it.
In my opinion, it is unlikely some other project except uClibc will be
affected by this change.
Best regards,
Cupertino
On 06/06/2017 02:19 PM, Nick Clifton wrote:
> Hi Cupertino,
>
>> From: Vineet Gupta <vgupta@synopsys.com>
>>
>> Historically the arc abi demanded that a GOT[0] should be referencible as
>> [pc+_DYNAMIC@gotpc]. Hence we convert a _DYNAMIC@gotpc to a GOTPC reference to
>> _GLOBAL_OFFSET_TABLE_.
>>
>> This is no longer the case and uClibc and upcomming GNU libc don't expect this
>> to happen.
> Is there going to be a legacy problem with this change to the ABI ?
>
> IE is it possible that code compiled with the old ABI will be linked with code
> compiled with the new ABI, and hence run into problems ?
>
> Cheers
> Nick
>