Re: How to "register" a GSI for a non PCI non ISA device

[Guillaume Knispel <gknispel@proformatique.com>]

On Wed, 25 Jan 2012 14:02:14 -0500
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> wrote:

> On Wed, Jan 25, 2012 at 06:23:14PM +0100, Guillaume Knispel wrote:
> > On Wed, 25 Jan 2012 00:56:53 -0500
> > Len Brown <lenb@kernel.org> wrote:
> > 
> > > What is the benefit of implementing ACPI on this custom system?
> > 
> > For our short term project it seems to be more a necessity than a
> > benefit. ACPI is supported by the SoC, tables are already largely
> > provided by Coreboot, the whole x86 ecosystem including Linux is more
> > or less based around ACPI, and my whole interrogation comes from the
> > fact that *acpi*_register_gsi() seems to be necessary to configure a
> > GSI in the APIC but is not exported anymore, so my guess is that if I
> 
> Hm, isn't it __acpi_register_gsi?

__acpi_register_gsi exists on recent kernels, it is the pointer to
the underlying implementation of that function depending on the
platform (x86 / xen-x86) and on the variant of the platform (pic/apic).
acpi_register_gsi still exists and it calls __acpi_register_gsi.

> > can't call it explicitly from my LKM, there should better be a way to
> > make it be called when an ACPI thing is done, or maybe a legacy table
> > parsed.
> 
> Can you do it the way xen does? Look in arch/x86/xen/pci.c

Did not found this file. Besides, isn't Xen a separate architecture
from mainline x86, compiled built-in? My goal is to only touch LKM and
system firmware if necessary.

> > As we first target an unmodified (if possible) 2.6.32 kernel from
> > Debian Squeeze, I can't just re-export acpi_register_gsi() and call it
> > a day. (If I've no other choice I'll obviously do it, but this would be
> > quite bad for future maintenance).
> 
> Oh wow. That is ancient. 3.2?

3.2 when a Debian stable will feature 3.2 :)

-- 
Guillaume Knispel
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