Re: [review v3] slotinfo in struct dtv_slotinfo_list should be flexible array [BZ #25...

[Sandra Loosemore <sandra@codesourcery.com>]

On 11/12/19 3:14 PM, Carlos O'Donell wrote:

> If the new glibc cannot be compiled with gcc8 or gcc9 for nios2, then that's
> a problem though. It immediately makes it difficult to test a new glibc on
> existing systems without upgrading the system compiler.
> 
> If there is a backend bug then it absolutely needs to be fixed, and it looks
> like Sandra will try that, but that won't reach the affected compilers until
> much much later.
> 
> I dislike backing out the changes you made because they are quite nice
> cleanups, and the downstream vendors tend to upgrade glibc and gcc and binutils
> all in one big group to avoid these issues so I don't expect they will ever
> see this problem. It's only us as developers that see the larger version
> skew problem.

IIUC Intel uses whatever versions of binutils/gcc/glibc that Mentor 
Graphics gives them (currently 2.32/9.2/2.30 respectively) in their SDK 
and does not mess with mainline trunk sources at all.  I can raise the 
issue with them, but IIRC this would not be the first time some changes 
have been made to glibc that require newish tools for building it.

> My inclination is to fix the gcc problem, backport the solution to the active
> FSF branches, and then that fixes our testers.
> 
> In order of importance:
> - Fix all gcc10 issues.
> - Fix the nios2 backend issue.
> - Backport nios2 backend to active FSF branches.
> - Rebuild and test to make sure we are all clean again.

Yes, that's my plan.

> How long will that take and is it OK to leave things in a broken state for that long
> for a given target like nios2?

Preparing and testing a patch for the Nios II GCC bug might take a 
couple days, but I have another one ahead of it in my queue that I'm 
trying to finish before Stage 1 closes at the end of the week.  So maybe 
a week maximum?

BTW, does this problem affect any other target that tries to use 
GP-relative addressing for small data, like MIPS?

-Sandra