Re: [PATCH v3 12/12] kdump: Use vmlinux_build_id to simplify

Stephen Boyd
2021-04-08T19:58:28Z

Quoting Baoquan He (2021-04-08 03:17:43)
> On 04/07/21 at 07:03pm, Petr Mladek wrote:
> > On Tue 2021-03-30 20:05:20, Stephen Boyd wrote:
> > > We can use the vmlinux_build_id array here now instead of open coding
> > > it. This mostly consolidates code.
> > >
> > > Cc: Jiri Olsa <jolsa@kernel.org>
> > > Cc: Alexei Starovoitov <ast@kernel.org>
> > > Cc: Jessica Yu <jeyu@kernel.org>
> > > Cc: Evan Green <evgreen@chromium.org>
> > > Cc: Hsin-Yi Wang <hsinyi@chromium.org>
> > > Cc: Dave Young <dyoung@redhat.com>
> > > Cc: Baoquan He <bhe@redhat.com>
> > > Cc: Vivek Goyal <vgoyal@redhat.com>
> > > Cc: <kexec@lists.infradead.org>
> > > Signed-off-by: Stephen Boyd <swboyd@chromium.org>
> > > ---
> > > include/linux/crash_core.h | 6 +-----
> > > kernel/crash_core.c | 41 ++------------------------------------
> > > 2 files changed, 3 insertions(+), 44 deletions(-)
> > >
> > > diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> > > index 206bde8308b2..fb8ab99bb2ee 100644
> > > --- a/include/linux/crash_core.h
> > > +++ b/include/linux/crash_core.h
> > > @@ -39,7 +39,7 @@ phys_addr_t paddr_vmcoreinfo_note(void);
> > > #define VMCOREINFO_OSRELEASE(value) \
> > > vmcoreinfo_append_str("OSRELEASE=%s\n", value)
> > > #define VMCOREINFO_BUILD_ID(value) \
> > > - vmcoreinfo_append_str("BUILD-ID=%s\n", value)
> > > + vmcoreinfo_append_str("BUILD-ID=%20phN\n", value)
>
> I may miss something, wondering why we need add '20' here.

The build ID is an array of 20 bytes and this format is to print 20
bytes in hex.