Re: [PATCH pahole 2/2] btf_encoder: run BTF deduplication before writing out to ELF

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Mon, Feb 18, 2019 at 11:38:41AM -0800, Andrii Nakryiko escreveu:
> On Mon, Feb 18, 2019 at 6:29 AM Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com> wrote:
> > Em Sun, Feb 17, 2019 at 12:20:18AM -0800, Andrii Nakryiko escreveu:
> > The 'struct sun_disklabel' is interesting, pahole doesn't print it for
> > the DWARF case when pretty printing all structs, but it works for the
> > BTF case, I'll investigate.
 
> I wonder if that has something to do with the fact that btf_dedup also
> does FWD -> STRUCT/UNION resolution?

Nope, when printing the classes (structs and class) pahole has this
show_private_classes option, so that structs and classes that are
defined inside other classes or functions are only shown when you ask
for that, and that is what sun_disklabel is, it is defined in
block/partitions/sun.c as:

int sun_partition(struct parsed_partitions *state)
{
        int i;
        __be16 csum;
        int slot = 1;
        __be16 *ush;
        Sector sect;
        struct sun_disklabel {
                unsigned char info[128];   /* Informative text string */
                struct sun_vtoc {
                    __be32 version;     /* Layout version */
                    char   volume[8];   /* Volume name */
                    __be16 nparts;      /* Number of partitions */
                    struct sun_info {           /* Partition hdrs, sec 2 */
                        __be16 id;
                        __be16 flags;
                    } infos[8];
<SNIP>

This information gets lost when we convert it to BTF, so for btfdiff
I'll add that option:

      --show_private_classes Show classes that are defined inside other classes
                             or in functions

When printing from DWARF info.

- Arnaldo