Re: [ARM/FDPIC v5 03/21] [ARM] FDPIC: Force FDPIC related options unless -mno-fdpic is provided

[Szabolcs Nagy <Szabolcs.Nagy@arm.com>]

On 15/05/2019 16:37, Rich Felker wrote:
> On Wed, May 15, 2019 at 05:12:11PM +0200, Christophe Lyon wrote:
>> On Wed, 15 May 2019 at 16:37, Rich Felker <dalias@libc.org> wrote:
>>> On Wed, May 15, 2019 at 01:55:30PM +0000, Szabolcs Nagy wrote:
>>>> can support both normal elf and fdpic elf so you can test/use
>>>> an fdpic toolchain on a system with mmu, but this requires
>>>> different dynamic linker name ..otherwise one has to run
>>>> executables in a chroot or separate mount namespace to change
>>>> the dynamic linker)
>>>
>>> Indeed, it's a bad idea to make them clash.
>>>
>>
>> Not sure to understand your point: indeed FDPIC binaries work
>> on a system with mmu, provided you have the right dynamic
>> linker in the right place, as well as the needed runtime libs (libc, etc....)
>>
>> Do you want me to change anything here?
> 
> I think the concern is that if the PT_INTERP name is the same for
> binaries with different ABIs, you wouldn't be able to have both
> present in the same root fs, and this would make it more of a pain to
> debug fdpic binaries on a full (with-mmu) host.
> 
> musl always uses a different PT_INTERP name for each ABI combination,
> so I guess the question is whether uclibc or whatever other libc
> you're intending people to use would also want to do this.

glibc uses different names now for new abis, so i was expecting
some *_DYNAMIC_LINKER update, but it seems uclibc always uses
the same fixed name

/lib/ld-uClibc.so.0

i guess it makes sense for them since iirc uclibc can change
its runtime abi based on lot of build time config so having
different name for each abi variant may be impractical.