[ELDK] linux 2.6.24 hangs after print "Uncompressing Kernel Image ... OK"

Wolfgang Denk wd at denx.de
Tue Oct 27 10:04:40 CET 2009

Dear =?GB2312?B?wdbWvsa9?=,

In message <8148211e0910262214h20195502k9ab1e2640375576d at mail.gmail.com> you wrote:
> when uboot gets reboot, contents in ddr will be lost.
> because uboot will initilize the memory control, which is longer than the
> ddr refresh cycle.
> And during these time, ddr contents will lost.

That's the theory, yes. There is no guarantee that the memory contnt
will remain in place unchanged or at all.

> So how can the contents in ddr be reserved after rebooting uboot.

Memory cells don't use their content immediately. Usually they will
keep their content for many milliseconds, often even seconds, before
single bits start flipping. Usually U-Boot startup is fast enough to
keep all memory content in place unchanged. Of course, you cannot
guarantee for this, but it works pretty reliably - and in any case
good enough for debugging purposes.

Why don't you just try it out?

Best regards,

Wolfgang Denk

DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
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