[Xen-devel] [PATCH v4 4/9] version: Print build-id at bootup.

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

Livepatch expected at some point to be able to print the
build-id during bootup, which it did not.  The reason is
that xen_build_init and livepatch_init are both __initcall
type routines. This meant that when livepatch_init called
xen_build_id, it would return -ENODATA as build_id_len was
not setup yet (b/c xen_build_init would be called later).

The original patch fixed this by calling xen_build_init in
livepatch_init which allows us to print the build-id of
the hypervisor.

However the x86 maintainers pointed out that build-id
is independent of Livepatch and in fact should print
regardless whether Livepatch is enabled or not.

Therefore this patch moves the logic of printing the build-id
to version.c.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

---
Cc: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>

v2: Move xen_build_init in version.h instead of livepatch.h
v3: Posted as "livepatch: Sync cache of build-id before using it first time"
v4: Move the printing of build-id to version.c.
    Change title
---
 xen/common/livepatch.c | 6 ------
 xen/common/version.c   | 7 ++++++-
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/xen/common/livepatch.c b/xen/common/livepatch.c
index 88f1543..bd65712 100644
--- a/xen/common/livepatch.c
+++ b/xen/common/livepatch.c
@@ -1579,12 +1579,6 @@ static void livepatch_printall(unsigned char key)
 
 static int __init livepatch_init(void)
 {
-    const void *binary_id;
-    unsigned int len;
-
-    if ( !xen_build_id(&binary_id, &len) )
-        printk(XENLOG_INFO LIVEPATCH ": build-id: %*phN\n", len, binary_id);
-
     register_keyhandler('x', livepatch_printall, "print livepatch info", 1);
 
     arch_livepatch_init();
diff --git a/xen/common/version.c b/xen/common/version.c
index b2afe96..74346b8 100644
--- a/xen/common/version.c
+++ b/xen/common/version.c
@@ -121,6 +121,7 @@ static int __init xen_build_init(void)
 {
     const Elf_Note *n = __note_gnu_build_id_start;
     unsigned int sz;
+    int rc;
 
     /* --build-id invoked with wrong parameters. */
     if ( __note_gnu_build_id_end <= &n[0] )
@@ -132,7 +133,11 @@ static int __init xen_build_init(void)
 
     sz = (void *)__note_gnu_build_id_end - (void *)n;
 
-    return xen_build_id_check(n, sz, &build_id_p, &build_id_len);
+    rc = xen_build_id_check(n, sz, &build_id_p, &build_id_len);
+    if ( !rc )
+        printk(XENLOG_INFO "build-id: %*phN\n", build_id_len, build_id_p);
+
+    return rc;
 }
 __initcall(xen_build_init);
 #endif
-- 
2.4.11


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