Re: bpf_errno. Was: [PATCH RFC bpf-next 1/3] bpf: report probe fault to BPF stderr

[Alexei Starovoitov]

On Thu, Oct 9, 2025 at 7:15 AM Leon Hwang <hffilw...@gmail.com> wrote:
>
>
> The verifier can rewrite 'bpf_reg_aux()' into the following instructions:
>
> dst_reg = BPF_REG_AUX;
> BPF_REG_AUX = 0; /* clear BPF_REG_AUX */
>
> As for the architecture-specific implementation, BPF_REG_AUX can be
> mapped to an appropriate register per arch — for example, r11 on x86_64.

it's taken. There are no free registers.