coreboot: introduce CONFIG_RELOCATABLE_RAMSTAGE
This patch adds an option to build the ramstage as a reloctable binary.
It uses the rmodule library for the relocation. The main changes
consist of the following:
1. The ramstage is loaded just under the cmbem space.
2. Payloads cannot be loaded over where ramstage is loaded. If a payload
is attempted to load where the relocatable ramstage resides the load
is aborted.
3. The memory occupied by the ramstage is reserved from the OS's usage
using the romstage_handoff structure stored in cbmem. This region is
communicated to ramstage by an CBMEM_ID_ROMSTAGE_INFO entry in cbmem.
4. There is no need to reserve cbmem space for the OS controlled memory for
the resume path because the ramsage region has been reserved in #3.
5. Since no memory needs to be preserved in the wake path, the loading
and begin of execution of a elf payload is straight forward.
Change-Id: Ia66cf1be65c29fa25ca7bd9ea6c8f11d7eee05f5
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/2792
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@google.com>
diff --git a/src/lib/selfboot.c b/src/lib/selfboot.c
index f32bb81..f933142 100644
--- a/src/lib/selfboot.c
+++ b/src/lib/selfboot.c
@@ -78,6 +78,16 @@
static unsigned long bounce_size, bounce_buffer;
+#if CONFIG_RELOCATABLE_RAMSTAGE
+static void get_bounce_buffer(struct lb_memory *mem, unsigned long req_size)
+{
+ /* When the ramstage is relocatable there is no need for a bounce
+ * buffer. All payloads should not overlap the ramstage.
+ */
+ bounce_buffer = ~0UL;
+ bounce_size = 0;
+}
+#else
static void get_bounce_buffer(struct lb_memory *mem, unsigned long req_size)
{
unsigned long lb_size;
@@ -114,6 +124,7 @@
bounce_buffer = buffer;
bounce_size = req_size;
}
+#endif /* CONFIG_RELOCATABLE_RAMSTAGE */
static int valid_area(struct lb_memory *mem, unsigned long buffer,
unsigned long start, unsigned long len)
@@ -394,8 +405,13 @@
for(ptr = head->next; ptr != head; ptr = ptr->next) {
if (!overlaps_coreboot(ptr))
continue;
+#if CONFIG_RELOCATABLE_RAMSTAGE
+ /* payloads are required to not overlap ramstage. */
+ return 0;
+#else
if (ptr->s_dstaddr + ptr->s_memsz > bounce_high)
bounce_high = ptr->s_dstaddr + ptr->s_memsz;
+#endif
}
get_bounce_buffer(mem, bounce_high - lb_start);
if (!bounce_buffer) {