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From: Nam Cao <namcao@linutronix.de>
To: Nilay Shroff <nilay@linux.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org, maddy@linux.ibm.com,
	mpe@ellerman.id.au, npiggin@gmail.com,
	christophe.leroy@csgroup.eu, tglx@linutronix.de, maz@kernel.org,
	gautam@linux.ibm.com, Gregory Joyce <gjoyce@ibm.com>
Subject: Re: [bug report] powerpc: per device MSI irq domain
Date: Thu, 04 Dec 2025 11:48:24 +0100	[thread overview]
Message-ID: <87qztawmiv.fsf@yellow.woof> (raw)
In-Reply-To: <6af2c4c2-97f6-4758-be33-256638ef39e5@linux.ibm.com>

Hi Nilay,

Nilay Shroff <nilay@linux.ibm.com> writes:
> I have been using an NVMe disk on my PowerPC system that supports up to
> 129 MSI-X interrupt vectors. Everything worked fine until Linux kernel
> v6.18, after which the NVMe driver stopped detecting the disk because
> the driver probe now fails.
>
> After further investigation, I found that the probe failure in v6.18
> occurs during PCI/MSI-X vector allocation. A git bisect identified
> commit daaa574aba6f (“powerpc/pseries/msi: Switch to msi_create_parent_
> irq_domain()”) as the first bad commit.

Thanks for the report. I can (kind of) reproduce the problem with QEMU.

I think moving rtas_prepare_msi_irqs() into pseries_irq_domain_alloc()
should resolve the problem. But I'm not sure because I don't understand
how RTAS works.

Does IBM have some documentation describing the RTAS API? I failed to
google it.

Best regards,
Nam


  reply	other threads:[~2025-12-04 10:48 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-12-02 11:17 [bug report] powerpc: per device MSI irq domain Nilay Shroff
2025-12-04 10:48 ` Nam Cao [this message]
2025-12-04 17:24   ` Nilay Shroff
2025-12-06 14:38     ` Nam Cao
2025-12-08 12:03       ` Nilay Shroff

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