K, thank you so far! I hoped there was an easier solution like a #define
in a header somewhere.
However it's the code I've gone through so far is already interesting as
coreboot often seems to use a refresh rate of ~16ms what's 4x of the
rate some vendors use.
// P.
On 20.03.2017 13:34, Arthur Heymans wrote:
Philipp Stanner <[email protected]> writes:
Hi,
where (which code file) does coreboot set the DRAM-refresh-rate and
how easy is it for me to change it?
That would be in raminit, which is platform specific. So it depends on
readability of that code whether it's easy to find or not.
Not sure of this is possible with raminits like FSP or MRC.bin provided
in binary only.
A higher refresh rate will decrease the performance but increase the
protection against Rowhammer.
// Philipp
Some example of how to achieve this on Intel 945 northbridge:
diff --git a/src/northbridge/intel/i945/raminit.c
b/src/northbridge/intel/i945/raminit.c
index b5cce9c429..36dd601fb2 100644
--- a/src/northbridge/intel/i945/raminit.c
+++ b/src/northbridge/intel/i945/raminit.c
@@ -811,32 +811,8 @@ static void sdram_detect_smallest_refresh(struct sys_info
* sysinfo)
{
int i;
- sysinfo->refresh = 0;
+ sysinfo->refresh = 1;
- for (i = 0; i < 2*DIMM_SOCKETS; i++) {
- int refresh;
-
- if (sysinfo->dimm[i] == SYSINFO_DIMM_NOT_POPULATED)
- continue;
-
- refresh = spd_read_byte(get_dimm_spd_address(sysinfo, i),
- SPD_REFRESH) & ~(1 << 7);
-
- /* 15.6us */
- if (!refresh)
- continue;
-
- /* Refresh is slower than 15.6us, use 15.6us */
- if (refresh > 2)
- continue;
-
- if (refresh == 2) {
- sysinfo->refresh = 1;
- break;
- }
-
- die("DDR-II module has unsupported refresh value\n");
- }
printk(BIOS_DEBUG, "Refresh: %s\n", sysinfo->refresh?"7.8us":"15.6us");
}
--
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