Re: [PATCH, RFC, RFT] ARM relocation fixes

[Vladimir 'φ-coder/phcoder' Serbinenko]

On 02.12.2013 21:46, Leif Lindholm wrote:
> On Mon, Dec 02, 2013 at 09:04:47PM +0100, Vladimir 'φ-coder/phcoder' 
> Serbinenko wrote:
>>>>> My default ARMv7 UEFI build fails to grub-install with
>>>>> /work/local/grub/uefi/sbin/grub-install: error: bl/b.w targettting ARM.
>>>>
>>>> This is a problem because of asm functions which are always ARM and gcc
>>>> uses bl to jump to them from thumb that an't be satisified. I wonder if
>>>> it's better to add veneers to mkimage or to add explicit thumb interwork
>>>> to all asm functions like I did in my other patch.
>>>
>>> Ah. When linking with a standalone linker, it rewrites BL to BLX where
>>> this is required for state change
>>
>> Doesn't this require Thumb2 ?
> 
> No, BLX immediate has been supported since ARMv5T.
> (Yes, that is effectively a 32-bit encoding in what is a 16-bit
> instruction set - but so is the basic BL.)
> 
I've looked through encoding of those instructions and see how much it's
a mess. b* and b*x don't have similar set of options which makes
validating them a difficult error-prone task. So I think, I'll just add
veneers to mkimage, just like we do on ia64 (either by making a
pc-relative variant of veneers or adding fixup for them)
> /
>     Leif
> 
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