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From: Paul Mackerras <paulus@samba.org>
To: michael@ellerman.id.au
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
	tony.luck@intel.com, grundler@parisc-linux.org, jeff@garzik.org,
	linux-kernel@vger.kernel.org, kyle@parisc-linux.org,
	linuxppc-dev@ozlabs.org, linux-pci@atrey.karlin.mff.cuni.cz,
	brice@myri.com, greg@kroah.com, shaohua.li@intel.com,
	mingo@elte.hu, David Miller <davem@davemloft.net>
Subject: Re: [PATCH 0/6] MSI portability cleanups
Date: Tue, 30 Jan 2007 10:29:07 +1100	[thread overview]
Message-ID: <17854.33603.655565.110084@cargo.ozlabs.ibm.com> (raw)
In-Reply-To: <1170065487.19887.91.camel@concordia.ozlabs.ibm.com>

Michael Ellerman writes:

> You can read config space, but it's not clear to me if the HV is allowed
> to filter it and hide things. It's also possible that the device

It appears that the HV does not prevent us from reading or writing any
config space registers for functions that are assigned to us.

> supports MSI, but for some reason the HV doesn't allow it on that device
> etc. so you really have to ask the HV if it's enabled. So pci_find_cap()
> shouldn't crash or anything, but it may lie to you.

It's possible that the device can do MSI(X), but that using MSI(X)
requires other platform resources (e.g. interrupt source numbers) and
there are none free.  I believe the platform guarantees a minimum
number of MSI(X) interrupts per function, but a pci_enable_msix() call
may not be able to give the driver as many MSI-X interrupts as it is
requesting even if the function can handle that many.

Paul.

  parent reply	other threads:[~2007-01-29 23:29 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1169714047.65693.647693675533.qpush@cradle>
2007-01-28 19:40 ` Eric W. Biederman
2007-01-28 19:42   ` [PATCH 1/6] msi: Kill msi_lookup_irq Eric W. Biederman
2007-01-28 19:44     ` [PATCH 2/6] msi: Remove msi_lock Eric W. Biederman
2007-01-28 19:45       ` [PATCH 3/6] msi: Fix msi_remove_pci_irq_vectors Eric W. Biederman
2007-01-28 19:47         ` [PATCH 4/6] msi: Remove attach_msi_entry Eric W. Biederman
2007-01-28 19:52           ` [PATCH 5/6] msi: Kill the msi_desc array Eric W. Biederman
2007-01-28 19:56             ` [PATCH 6/6] msi: Make MSI useable more architectures Eric W. Biederman
2007-01-28 22:01     ` [PATCH 1/6] msi: Kill msi_lookup_irq Paul Mackerras
2007-01-28 22:18       ` Eric W. Biederman
2007-01-28 20:23   ` [PATCH 0/6] MSI portability cleanups Benjamin Herrenschmidt
2007-01-28 20:47     ` Jeff Garzik
2007-01-28 21:20       ` Eric W. Biederman
2007-01-28 21:26         ` Ingo Molnar
2007-01-28 22:09         ` Benjamin Herrenschmidt
2007-01-28 23:26           ` Eric W. Biederman
2007-01-28 23:37             ` David Miller
2007-01-29  5:18               ` Eric W. Biederman
2007-01-29  5:25                 ` David Miller
2007-01-29  5:58                   ` Eric W. Biederman
2007-01-29  6:05                   ` Benjamin Herrenschmidt
2007-01-29  8:28                     ` Eric W. Biederman
2007-01-29  9:03                     ` Eric W. Biederman
2007-01-29 10:11                       ` Michael Ellerman
2007-01-29 20:32                         ` Benjamin Herrenschmidt
2007-01-29 23:29                         ` Paul Mackerras [this message]
2007-01-29 23:40                           ` Benjamin Herrenschmidt
2007-01-29 20:22                       ` Benjamin Herrenschmidt
2007-01-29 23:05                         ` Paul Mackerras
2007-01-30 19:32                           ` Segher Boessenkool
2007-01-29  1:33             ` Benjamin Herrenschmidt
2007-02-01  4:29           ` Greg KH
2007-01-28 23:44         ` David Miller
2007-01-28 22:11       ` Eric W. Biederman
2007-01-28 23:42       ` David Miller
2007-01-28 21:34     ` Eric W. Biederman

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