Re: Wrong CPU count on Apollo Lake platform

[Jan Kiszka <jan.kiszka@siemens.com>]

On 20.05.22 13:41, dabbede--- via Xenomai wrote:
> Dear Xenomai community,
> 
> I'm writing here because of the following issue: I have compiled a
> xenomai-patched kernel that, when used on an Intel Atom E3950 (Apollo
> Lake family), return the wrong cpu count (i.e. nproc returns 1 instead
> of 4, and also lscpu claims CPU(s): 1).
> The very same kernel, when run on an Intel i5-7440EQ, returns nproc=4,
> which is correct.
> I'm using CONFIG_GENERIC_CPU=y, and this, to my knowledge, should be a
> safer option to handle both Atom and i5 or other platforms. I've also
> tried to use CONFIG_MATOM or CONFIG_MCORE2 without noticeable
> differences.
> 
> I attach here the full config and the dmesg that I obtain on the two
> platforms. Comparing the logs I've noticed the message "BIOS bug, no
> explicit IRQ entries, using default mptable. (tell your hw vendor)"
> but I'm not sure whether this is the cause or an effect of the
> problem.
> 
> Can you help me suggesting which CONFIG option I should change?
> 

[    0.057400] Processor #0 (Bootup-CPU)
[    0.057403] BIOS bug, no explicit IRQ entries, using default mptable. (tell your hw vendor)
[    0.057412] Processors: 1
[    0.057416] smpboot: Allowing 1 CPUs, 0 hotplug CPUs

Seems first of all unrelated to Xenomai.

Did you already try to compile a Xenomai/I-pipe free kernel with 
defconfig settings, whether that is able to detect all CPUs? If not, you 
should really look for a BIOS update of your board. Or complain with its 
vendor about breaking standards and, thus, Linux.

Jan

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