libpayload: Add comments on virtual pointers in lib_sysinfo

After another incident related to virtual pointers in lib_sysinfo (and
resulting confusion), I decided to put some comments on the matter into
the code.

Remember, we decided to always use virtual pointers in lib_sysinfo, but
it's not always obvious from the code, that they are.

See also:
425973c libpayload: Always use virtual pointers in struct sysinfo_t
593f577 libpayload: Fix use of virtual pointers in sysinfo

Change-Id: I886c3b1d182cba07f1aab1667e702e2868ad4b68
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: http://review.coreboot.org/2878
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/payloads/libpayload/include/sysinfo.h b/payloads/libpayload/include/sysinfo.h
index 4c7ce4521b..e05ef9f4d6 100644
--- a/payloads/libpayload/include/sysinfo.h
+++ b/payloads/libpayload/include/sysinfo.h
@@ -39,6 +39,12 @@
 
 struct cb_serial;
 
+/*
+ * All pointers in here shall be virtual.
+ *
+ * If a relocation happens after the last call to lib_get_sysinfo(),
+ * it is up to the user to call lib_get_sysinfo() again.
+ */
 struct sysinfo_t {
 	unsigned int cpu_khz;
 	struct cb_serial *serial;