[LEDE-DEV] [PATCH 2/2] toolchain: gcc: drop MIPS patch

[Arjen de Korte]

Citeren Kevin Darbyshire-Bryant <kevin at darbyshire-bryant.me.uk>:

> On 23/08/17 09:20, Felix Fietkau wrote:
>> On 2017-08-22 12:01, Kevin Darbyshire-Bryant wrote:
>>> Drop 300-mips_Os_cpu_rtx_cost_model.patch for gcc 7.2
>>>
>>> This was causing mis-compilation of dropbear with the default '-Os' size
>>> optimization as reported in FS#814
>>>
>>> Tested on ar71xx, archer C7 v2.  For size comparison of my whole build:
>>>
>>> 12058628 O2-withoutpatch-dropbearworks.bin
>>> 12058628 O2-withpatch-dropbearworks.bin
>>> 11468804 Os-withoutpatch-dropbearworks.bin
>>> 11468804 Os-withpatch-dropbearfails.bin
>>>
>>> Signed-off-by: Kevin Darbyshire-Bryant <kevin at darbyshire-bryant.me.uk>
>> I strongly suspect that this change is hiding the real bug instead of
>> fixing it. Please double-check that the mis-compilation also does not
>> happen with -O2 instead of -Os.
>>
>> - Felix
>>
>
> To further expand on this:  I switched from the 74kc cpu target to  
> 24kc (which is the lede default)
>
> 11993092 24O2-withoutpatch-works.bin
> 12058628 24O2-withpatch-works.bin
> 11403268 24Os-withoutpatch-works.bin
> 11468804 24Os-withpatch-fails.bin
>
> 2 observations: The working/not working follows the same pattern as  
> found with 74kc.  Sizes on 24kc are always larger with the patch.

While removing the MIPS patch fixes dropbear when using gcc 7.1.0 and  
'-Os', uhttpd goes tits up with a segfault in liblua. With '-O2' it's  
fine for both, so I'll probably stick with that for now.