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Subject: Re: [PATCH v3 12/12] kdump: Use vmlinux_build_id to simplify
From:   Stephen Boyd <swboyd@chromium.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, Jiri Olsa <jolsa@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Jessica Yu <jeyu@kernel.org>,
        Evan Green <evgreen@chromium.org>,
        Hsin-Yi Wang <hsinyi@chromium.org>,
        Dave Young <dyoung@redhat.com>,
        Vivek Goyal <vgoyal@redhat.com>, kexec@lists.infradead.org
To:     Baoquan He <bhe@redhat.com>, Petr Mladek <pmladek@suse.com>
Date:   Thu, 08 Apr 2021 12:58:24 -0700
Message-ID: <161791190437.3790633.11239676305383366588@swboyd.mtv.corp.google.com>
User-Agent: alot/0.9.1
Precedence: bulk

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.
> > >=20
> > > 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(-)
> > >=20
> > > 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=3D%s\n", value)
> > >  #define VMCOREINFO_BUILD_ID(value) \
> > > -   vmcoreinfo_append_str("BUILD-ID=3D%s\n", value)
> > > +   vmcoreinfo_append_str("BUILD-ID=3D%20phN\n", value)
>=20
> 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.