[coreboot] Google Panther: coreboot has to wait for Intel’s ME (Management Engine)

[Matt DeVillier]

On 4/26/2015 3:03 AM, Paul Menzel wrote:
> Dear coreboot folks,
>
>
> looking at the time stamps of the Intel Haswell device Google Panther,
> which Matt DeVillier thankfully uploaded to the board status repository
> [1], it looks odd that it took around a quarter of a second, from after
> the SeaBIOS payload was decompressed to starting the payload. This is
> almost half of the whole boot time.
>
>         […]
>           90:load payload                                      233,302 (216)
>           15:starting LZMA decompress (ignore for x86)         233,415 (113)
>           16:finished LZMA decompress (ignore for x86)         250,327 (16,912)
>           99:selfboot jump                                     493,712 (243,384)
>
> Thanks to Aaron Durbin’s analysis of the code path, the finalize in line
> 138 of `src/southbridge/intel/lynxpoint/smi.c` calls
> `intel_me_mbp_clear()` in line 589 of
> `src/southbridge/intel/lynxpoint/me_9.x.c`.
>
>         $ more src/southbridge/intel/lynxpoint/me_9.x.c # line 589
>         […]
>         #if CONFIG_ME_MBP_CLEAR_LATE
>         	/* Wait for ME MBP Cleared indicator */
>         	intel_me_mbp_clear(PCH_ME_DEV);
>         #endif
>         […]
>
> The issue is even described in the Kconfig option description of
> `ME_MBP_CLEAR_LATE` and the commit message of commit 3d299c4b (lynxpoint
> me: add support for mbp clear wait in finalize step) [2] adding this
> option.
>
>         $ more src/southbridge/intel/lynxpoint/Kconfig
>         […]
>         config ME_MBP_CLEAR_LATE
>         	bool "Defer wait for ME MBP Cleared"
>         	default y
>         	help
>         	  If you set this option to y, the Management Engine driver
>         	  will defer waiting for the MBP Cleared indicator until the
>         	  finalize step.  This can speed up boot time if the ME takes
>         	  a long time to indicate this status.
>         […]
>
> I guess there is no way to get fixed ME BLOBs from Intel. I heard the ME
> BLOB has been fixed for newer Intel devices.

The ME firmware that ships with Panther is 9.5.13.1706.  I've also tested 9.5.41.1904 (what I'm using in the firmware referenced above) and 9.5.45.1922 (which I just came across today) - all display the same behavior in terms of time needed to report MBP cleared.  The 9.6 series ME firmware is also for Haswell/Lynxpoint, but I'm unsure if it's compatible with systems shipped with ME 9.5.  Since I have an external programmer, I suppose I could always give it a try :)  The 10.0 series ME firmware is for Broadwell and is more likely to contain the fix, but less likely to be compatible with Haswell/LP.

-Matt

>
>
> Thanks,
>
> Paul
>
>
> [1] http://review.coreboot.org/gitweb?p=board-status.git;a=commitdiff;h=3926f95b143b74c0762516df0bdf250c1dd8ba32#patch4
> [2] http://review.coreboot.org/4375
>
>

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