ECC memory of BMC

[Stefan Schaeckeler (sschaeck)]

Hello Will,


One more thing about enabling ECC:

> ECC needs to be enabled in u-boot. The reason is explained in my first upload
> https://patchwork.kernel.org/patch/10732769/
> 
> Our u-boot engineer did it for us. I see u-boot code is full of #ifdef CONFIG_DRAM_ECC blocks.
> In theory, enabling this option should be enough.
> 
> 
> - A good indication of having ECC successfully enabled is linux actually booting.
> - Another indication is available memory being 8/9th of what it used to be (check /proc/meminfo)
> - Then, my driver should not log any errors in its probe function (check dmesg).


While you have not set up ECC mode in u-boot yet, you might be able to use the
edac driver by removing the following code in aspeed_probe()

	/* bail out if ECC mode is not configured */
	regmap_read(aspeed_regmap, ASPEED_MCR_CONF, &reg04);
	if (!(reg04 & ASPEED_MCR_CONF_ECC)) {
		dev_err(&pdev->dev, "ECC mode is not configured in u-boot\n");
		return -EPERM;
	}

This will run the probe function hopefully to the end and expose the sysfs nodes.
I have not tested it. Maybe you need to further butcher down the driver?


You can then inject fake ecc errors via the kernel debug framework:

root at aspeed-arm:/# echo 42 > /sys/kernel/debug/edac/mc0/fake_inject  

root at aspeed-arm:/# dmesg | tail -1
[  293.020000] EDAC MC0: 1 CE FAKE ERROR on mc#0csrow#0channel#0 (csrow:0 channel:0 page:0x0 offset:0x0 grain:0 syndrome:0x0 - for EDAC testing only)

root at aspeed-arm:/# cat /sys/devices/system/edac/mc/mc0/ce*
1
0


BTW, here are my notes on EDAC and ECC on Aspeed which you might find
interesting: http://students.engr.scu.edu/~sschaeck/misc/aspeed-edac.html



Hope that helps, Stefan