Messages in this thread | | | Date | Wed, 21 Aug 2019 10:34:55 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH] x86/apic: Update virtual irq base for DT/OF based system as well |
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On Wed, 21 Aug 2019, Rahul Tanwar wrote:
> 'ioapic_dynirq_base' contains the virtual IRQ base number. Presently, it is > updated to the end of hardware IRQ numbers but this is done only when IOAPIC > configuration type is IOAPIC_DOMAIN_LEGACY or IOAPIC_DOMAIN_STRICT. There is > a third type IOAPIC_DOMAIN_DYNAMIC which applies when IOAPIC configuration > comes from devicetree. > Please see dtb_add_ioapic() in arch/x86/kernel/devicetree.c
We know how DT based ioapics are added. No need to point to it.
> In case of IOAPIC_DOMAIN_DYNAMIC (DT/OF based system), 'ioapic_dynirq_base' > remains to zero initialized value. This means that for OF based systems, > virtual IRQ base will get set to zero. Zero value for a virtual IRQ is a > invalid value. > Please see https://yarchive.net/comp/linux/zero.html for more details.
First of all, please do not use random archive links. See Documentation/process/ how links to LKML archives should look like
Secondly, this link is irrelevant. ioapic_dynirq_base has nothing to do with virtual IRQ number 0. It's a boundary for the dynamic allocation of virtual interrupt numbers so that the core allocator does not pick interrupts out of the IOAPIC's fixed interrupt number space.
This can be legitimately 0 when IOAPIC is not enabled at all.
Can you please explain what kind of problem you were seing and what this really fixes?
Thanks,
tglx
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