[coreboot-gerrit] Patch set updated for coreboot: arch/x86: Include timestamp.c in all stages
Alexandru Gagniuc (alexandrux.gagniuc@intel.com)
gerrit at coreboot.org
Tue May 17 20:30:17 CEST 2016
Alexandru Gagniuc (alexandrux.gagniuc at intel.com) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/14860
-gerrit
commit 52a91672221cdba72a950cfce523a505439ee039
Author: Alexandru Gagniuc <alexandrux.gagniuc at intel.com>
Date: Mon May 16 14:22:00 2016 -0700
arch/x86: Include timestamp.c in all stages
timestamp.c was not included in bootblock and postcar. This means that
these two stages would use the weak implementation in lib/timestamp.c
instead of the arch-specific implementation based on rdtsc.
This resulted in using timer_monotonic_get() which resets the
timestamps from 0. timer_monotonic_get() only provides per-stage
incrementing semantics on x86 because lapic implementation has
counting down values. A globally incrementing counter like rdtsc
provides the semantics like every other non-x86.
On the test configuration, the weak implementation of timestamp_get()
returned zero, resulting in wrong timestamps coming from the bootblock,
while romstage and ramstage used the arch implementation and returned
correct timestamps.
This is a great example of why weak functions are dangerous, and how
easy it is to miss subtle yet strong interactions between subsystems
and the coreboot buildsystem.
Change-Id: I656f9bd58a6fc179d9dbbc496c5b684ea9288eb5
Signed-off-by: Alexandru Gagniuc <alexandrux.gagniuc at intel.com>
---
src/arch/x86/Makefile.inc | 2 ++
1 file changed, 2 insertions(+)
diff --git a/src/arch/x86/Makefile.inc b/src/arch/x86/Makefile.inc
index a363430..c27bb1a 100644
--- a/src/arch/x86/Makefile.inc
+++ b/src/arch/x86/Makefile.inc
@@ -97,6 +97,7 @@ ifeq ($(CONFIG_ARCH_BOOTBLOCK_X86_32)$(CONFIG_ARCH_BOOTBLOCK_X86_64),y)
bootblock-y += boot.c
bootblock-y += memcpy.c
bootblock-y += memset.c
+bootblock-$(CONFIG_COLLECT_TIMESTAMPS) += timestamp.c
bootblock-$(CONFIG_X86_TOP4G_BOOTMEDIA_MAP) += mmap_boot.c
bootblock-y += id.S
@@ -394,6 +395,7 @@ postcar-y += memset.c
postcar-y += memcpy.c
postcar-y += memmove.c
postcar-y += memlayout.ld
+postcar-$(CONFIG_COLLECT_TIMESTAMPS) += timestamp.c
postcar-$(CONFIG_X86_TOP4G_BOOTMEDIA_MAP) += mmap_boot.c
$(objcbfs)/postcar.debug: $$(postcar-objs)
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