New devolpments.
I have upgraded to 2.6.16.41, applied a patch sent by Frederik that
removed the changed made in http://lkml.org/lkml/2005/6/23/266 and
activated some more kernel debug, i.e., CONFIG_KALLSYMS_ALL,
CONFIG_DEBUG_KERNEL, CONFIG_DETECT_SOFTLOCKUP, CONFIG_DEBUG_SLAB,
CONFIG_DEBUG_MUTEXES, CONFIG_FRAME_POINTER and CONFIG_FORCED_INLINING
(thanks to vda for pointing me to the right doc.).
At first it seemed to work fine, but after some days of continuous
running I've got another kernel Oops!
I attach the dmesg output and the assembly dump of serial8250_startup()
and serial8250_shutdown().

Regards,
José Gonçalves