On 04/11/2022 15:59, Alexei Starovoitov wrote: > On Fri, Nov 4, 2022 at 7:35 AM KP Singh <kpsingh@xxxxxxxxxx> wrote: >> >> On Fri, Nov 4, 2022 at 6:16 AM Vitaly Chikunov <vt@xxxxxxxxxxxx> wrote: >>> >>> Hi, >>> >>> We need to reduce kernel size for aarch64, because it does not fit into >>> U-Boot loader on Raspberry Pi (due to it having fdt_addr_r=0x02600000) >>> and one of big ELF sections in vmlinuz is .BTF taking around 5MB. >>> Compression does not help because on aarch64 kernels are >>> uncompressed[1]. >>> >>> Is it theoretically possible to make sysfs_btf a module? >> >> I think so, it may need some refactoring and changes >> but, yeah, in theory, the module could ship with the >> kernel's BTF information which can then be initialized by the module. >> >> Curious to see what others think as well. > > Yeah. That request came up a few times. > Whoever has cycles to work on it... please go ahead :) > We've experimented with this a bit for the global variable patch series, where global variable BTF is a tristate config parameter, and if set to 'm' the BTF for variables ends up in vmlinux_btf_extra.ko instead (patch series forthcoming; it was stuck behind the dedup issues which took a while to uncover). One approach would be to extend that scheme such that CONFIG_DEBUG_INFO_BTF=m I guess? The only thing that might require change is the name; vmlinux_btf might be a more appropriate module name than vmlinux_btf_extra perhaps? Thanks! Alan
