[cfe-dev] LLD for ARM

Rui Ueyama ruiu at google.com
Thu Aug 21 17:38:31 PDT 2014


I ported LLD to Windows. I added a new file format, new driver, new
relocation types, new linking semantics and those kind of stuffs. I
remember that it took me a month or two to link a small executable,
starting from having no knowledge on Windows linker, and after about six
months I succeeded to self-link it. After one year it's now able to link
real large programs such as Chromium. I wanted to make it work as a drop in
replacement of link.exe, so I had to work on the driver  -- if I only
focused on the core linking it would have been shorter.

>From that experience I would say that you'd probably be able to get a
preliminary support of what you want in a few weeks to a few months. Of
course that depends on your knowledge of the target platform, availability
of the documents, etc. It shouldn't at least take years.


On Thu, Aug 21, 2014 at 4:43 PM, Daniel Dilts <diltsman at gmail.com> wrote:

> Right now I am working a proof of concept at work that I can use Clang and
> associated tools to compile for a bare metal ARM processor (Beaglebone
> Black).  The biggest issue seems to be that we develop on Windows and most
> cross linkers (ld, gold) seem to only want to work on POSIX, which is not
> Windows.  So far I have spent a day fighting binutils to get ld to compile
> on Windows to target ARM.
>
> For a complete novice, what would be the expected amount of effort (days,
> weeks, months, years) to add support for a new target?
>
>
> On Thu, Aug 21, 2014 at 1:31 PM, Renato Golin <renato.golin at linaro.org>
> wrote:
>
>> On 21 August 2014 17:20, Daniel Dilts <diltsman at gmail.com> wrote:
>> > I'm seeing that LLD has the initial framework for linking AArch64 (ARM
>> > 64-bit, right?).  Is there a plan or timeframe to support 32-bit ARM?
>>
>> Hi Daniel,
>>
>> The quick answer is "sort of".
>>
>> There is interest in having lld working well on both ARM Linux and
>> Darwin and some people are already gathering forces to do this, but
>> the interest is still not *that* great to make people jump on it right
>> now. Are you volunteering or needing this for any project? We could
>> certainly do with the help, or at least understand what are your
>> plans, so that we can align with them.
>>
>> cheers,
>> --renato
>>
>
>
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