BBB MMC / SD detection instability with U-Boot 2014.04 (CPU 1GHz)

[Warner Losh]

On May 19, 2014, at 9:36 PM, Sulev-Madis Silber (ketas) <madis555 at hot.ee> wrote:

> On 2014-05-20 05:39, Winston Smith wrote:
>> On Mon, May 19, 2014 at 10:28 PM, Warner Losh <imp at bsdimp.com> wrote:
>>> Wow! That’s a lot of added 10ms delays…  Do we have a theory of the crime
>>> for why they are needed? Usually they suggest to me that we’re doing something
>>> wrong (either not checking the right bits in the bridge, having a fixed retry count
>>> rather than a timed limit and having some bridges fail more slowly than others
>>> so the delays are effecting the same thing).
>> 
>> It's a good start (since the BBB is really flakey at 1Ghz), but yes,
>> more delays aren't good!
>> 
>> For what it's worth, I'm working in parallel with both FreeBSD and
>> Debian Wheezy images on the BBB, and it is quite apparent that the BBB
>> running FreeBSD is *much* slower to boot than the BBB running Debian;
>> which currently boots to the login prompt in about 15 seconds from
>> power up.  FreeBSD has a 15-20 second delay just to detect the eMMC,
>> let alone everything else.
>> 
>> Comparatively, my x64 FreeBSD VM boots much more quickly than my Ubuntu x64 VM.
>> 
>> -W.
>> 
> 
> 
> "really flakey" sounds like "unstable, panics 1000 times a day". I don't
> see any of that here (as of 11.0-CURRENT r266442).
> 
> Boot, hmm... yea, 1min (just measured) to fully boot up and connect to
> server (I'm using ethernet, DHCP, loader boot delay = 3, huge Perl
> program) might be too slow if you have some embedded system which
> constantly loses power or something... I haven't tried to do any boot
> time optimizations yet. Compress kernel? Compress userland? Execute
> something in parallel on init (NOTE: *DON'T* even think about porting
> Linux init replacements here)? Use rescue-like static binary? Heavily
> customize / patch kernel? Use own init? Use rootfs inside kernel?
> Actually I guess many people might think like me... "HELL, optimizing
> boot time of 1min?! I have more important tasks to do than this”.

Make MMC faster, and a lot of this will go away. When I was doing Atmel,
I got more milage out of optimizing the I/O path for slow boots than I did
for just about anything else.

Another quick hack: delete all files in /etc/rc.d that aren’t used.

Warner

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