anakryiko added a comment. In D74668#2020554 <https://reviews.llvm.org/D74668#2020554>, @yonghong-song wrote:
> In D74668#2019558 <https://reviews.llvm.org/D74668#2019558>, @anakryiko wrote: > > > what's the use case for flag==0 (no relocation)? why using built-in at all > > in such case? Also flag==1 means relocate to local BTF ID or remote > > (kernel) BTF ID? Do you plan to add flag=2 as well to cover both cases? Or > > am I misunderstanding the meaning of this flag? > > > Originally, I thought flag = 0 for the following use case: > > e.g., they just want to know the type of a particular local structure for > pretty print purpose. > Note that currently only types for global/extern variables, function > parameters are recorded in btf. > int test() { > struct { int a; int b; ...} ctx; > btf_id = __builtin_btf_type_id(ctx, 0); > bpf_seq_write(seq, &btf_id, sizeof(btf_id)); > bpf_seq_write(seq, &ctx, sizeof(ctx)); > ... > } > > But obviously without relocation, this will not work with btf > deduplication, future static linking etc. Right, that's what I was thinking. We should have relocation always, even if it's a noop for libbpf today. > flag 1: for relocation. My original thinking is for vmlinux relocation. > > > > I think you brought a good point about local relocation, so will need > to change the flag to: > > flag 0 : local relocation > flag 1: vmlinux relocation > > > Two more relocation types will be generated: > > BTF_TYPE_ID_LOCAL > BTF_TYPE_ID_REMOTE Yep, that would be great. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D74668/new/ https://reviews.llvm.org/D74668 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
