Re: [bpf-next:master 8/9] FAILED: load BTF from .tmp_vmlinux1.BTF.1: No such file or directory

Re: [bpf-next:master 8/9] FAILED: load BTF from .tmp_vmlinux1.BTF.1: No such file or directory

[Ihor Solodrai]

On 12/24/25 5:01 PM, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
> head:   f14cdb1367b947d373215e36cfe9c69768dbafc9
> commit: 522397d05e7d4a7c30b91841492360336b24f833 [8/9] resolve_btfids: Change in-place update with raw binary output
> config: nios2-randconfig-001-20251224 (https://download.01.org/0day-ci/archive/20251225/202512250932.X7mdviuH-lkp@intel.com/config)
> compiler: nios2-linux-gcc (GCC) 11.5.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251225/202512250932.X7mdviuH-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202512250932.X7mdviuH-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
>    Complex, interval and imaginary float types are not supported
>    Error while encoding BTF.

Hi Dinh, Alan,

Not sure why this has surfaced only now, but it appears that kernel
build with ARCH=nios2 and CONFIG_DEBUG_INFO_BTF=y has been broken for
a long time.

I tried the following revisions:
  - bpf-next @ 522397d05e7d as in bug report
  - bpf-next @ 014e1cdb5fad without the gen-btf.sh patch
  - v6.18
  - v6.17
  - v6.12 (~1y ago)

All fail with the same error in pahole [1]:

	Complex, interval and imaginary float types are not supported
	Encountered error while encoding BTF.

I used v1.24 in most experiments, the default debian:bookworm
installation.  Upgrading pahole to v1.31 doesn't change this behavior.

I also stumbled on a phoronix article [2], saying Nios II support has
ended with GCC 15. Is it actively supported in Linux?

Not clear to me if anything needs to be fixed here. I'd appreciate any input.

Thanks.

[1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/tree/btf_encoder.c?h=v1.31#n469
[2] https://www.phoronix.com/news/GCC-15-Drops-Altera-Nios-II


>>> FAILED: load BTF from .tmp_vmlinux1.BTF.1: No such file or directory
> 

Re: [bpf-next:master 8/9] FAILED: load BTF from .tmp_vmlinux1.BTF.1: No such file or directory

[Alan Maguire]

On 29/12/2025 19:28, Ihor Solodrai wrote:
> On 12/24/25 5:01 PM, kernel test robot wrote:
>> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
>> head:   f14cdb1367b947d373215e36cfe9c69768dbafc9
>> commit: 522397d05e7d4a7c30b91841492360336b24f833 [8/9] resolve_btfids: Change in-place update with raw binary output
>> config: nios2-randconfig-001-20251224 (https://download.01.org/0day-ci/archive/20251225/202512250932.X7mdviuH-lkp@intel.com/config)
>> compiler: nios2-linux-gcc (GCC) 11.5.0
>> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251225/202512250932.X7mdviuH-lkp@intel.com/reproduce)
>>
>> If you fix the issue in a separate patch/commit (i.e. not just a new version of
>> the same patch/commit), kindly add following tags
>> | Reported-by: kernel test robot <lkp@intel.com>
>> | Closes: https://lore.kernel.org/oe-kbuild-all/202512250932.X7mdviuH-lkp@intel.com/
>>
>> All errors (new ones prefixed by >>):
>>
>>    Complex, interval and imaginary float types are not supported
>>    Error while encoding BTF.
> 
> Hi Dinh, Alan,
> 
> Not sure why this has surfaced only now, but it appears that kernel
> build with ARCH=nios2 and CONFIG_DEBUG_INFO_BTF=y has been broken for
> a long time.
> 
> I tried the following revisions:
>   - bpf-next @ 522397d05e7d as in bug report
>   - bpf-next @ 014e1cdb5fad without the gen-btf.sh patch
>   - v6.18
>   - v6.17
>   - v6.12 (~1y ago)
> 
> All fail with the same error in pahole [1]:
> 
> 	Complex, interval and imaginary float types are not supported
> 	Encountered error while encoding BTF.
> 
> I used v1.24 in most experiments, the default debian:bookworm
> installation.  Upgrading pahole to v1.31 doesn't change this behavior.
> 
> I also stumbled on a phoronix article [2], saying Nios II support has
> ended with GCC 15. Is it actively supported in Linux?
> 
> Not clear to me if anything needs to be fixed here. I'd appreciate any input.
> 
> Thanks.

hi Ihor, it's probably worth separating the issue of complex/interval/imaginary
support from nios2 support. In terms of the latter, if the breakage is old I agree
that it is at least a lower priority. Did you figure out where the problematic
type comes from? Might be a workaround we could apply there.

It also does raise a valid issue about supporting a larger menu of floating-point
types supported by GNU C/C++. To do so it looks like we'd need 2 bits 
to support the range of possibilities 

- standard floating point
- complex floating point
- interval floating point
- imaginary floating point

Is there interest in supporting these? Thanks!

Alan
 
> 
> [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/tree/btf_encoder.c?h=v1.31#n469
> [2] https://www.phoronix.com/news/GCC-15-Drops-Altera-Nios-II
> 
> 
>>>> FAILED: load BTF from .tmp_vmlinux1.BTF.1: No such file or directory
>>
> 
>