linux-kernel - Re: [PATCH v2] powerpc/pci: unmap legacy INTx interrupts when a PHB is removed

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Date:   Tue, 3 Nov 2020 15:40:07 +1100
From:   "Oliver O'Halloran" <oohall@...il.com>
To:     Cédric Le Goater <clg@...d.org>
Cc:     Alexey Kardashevskiy <aik@...abs.ru>, Qian Cai <cai@...hat.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Linux-Next Mailing List <linux-next@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] powerpc/pci: unmap legacy INTx interrupts when a PHB
 is removed

On Tue, Nov 3, 2020 at 1:39 AM Cédric Le Goater <clg@...d.org> wrote:
>
> On 10/14/20 4:55 AM, Alexey Kardashevskiy wrote:
> >
> > How do you remove PHBs exactly? There is no such thing in the powernv platform, I thought someone added this and you are fixing it but no. PHBs on powernv are created at the boot time and there is no way to remove them, you can only try removing all the bridges.
>
> yes. I noticed that later when proposing the fix for the double
> free.
>
> > So what exactly are you doing?
>
> What you just said above, with the commands :
>
>   echo 1 >  /sys/devices/pci0031\:00/0031\:00\:00.0/remove
>   echo 1 >  /sys/devices/pci0031\:00/pci_bus/0031\:00/rescan

Right, so that'll remove the root port device (and Bus 01 beneath it),
but the PHB itself is still there. If it was removed the root bus
would also disappear.