From: Alistair Popple <alistair@popple.id.au>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: devicetree@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH 7/7] powerpc: Added PCI MSI support using the HSTA module
Date: Tue, 25 Feb 2014 16:54:58 +1100 [thread overview]
Message-ID: <1541869.UgdfUgWYNB@mexican> (raw)
In-Reply-To: <1393015286.6771.110.camel@pasglop>
On Sat, 22 Feb 2014 07:41:26 Benjamin Herrenschmidt wrote:
> On Fri, 2014-02-21 at 15:33 +0100, Arnd Bergmann wrote:
[...]
>
> Should we (provided it's possible in HW) create two ranges instead ? One
> covering RAM and one covering MSIs ? To avoid stray DMAs whacking random
> HW registers in the chip ...
>
The thought occurred to me but I figured if we had stray DMAs then they could
already whack random bits of system memory which would likely break your
system anyway so I wasn't sure how much we'd gain. I guess whacking random HW
registers is arguably a bit worse though.
I did a bit of digging into the HW documentation and it looks like it _may_ be
possible to create a second range that would limit access to a subset of HW
registers, although there doesn't seem to be much flexibility. Personally I'm
not sure it justifies the work, but I'm happy to look into it a bit more if
you feel it's important?
- Alistair
WARNING: multiple messages have this Message-ID (diff)
From: Alistair Popple <alistair-Y4h6yKqj69EXC2x5gXVKYQ@public.gmane.org>
To: Benjamin Herrenschmidt
<benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
Cc: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>,
devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
Subject: Re: [PATCH 7/7] powerpc: Added PCI MSI support using the HSTA module
Date: Tue, 25 Feb 2014 16:54:58 +1100 [thread overview]
Message-ID: <1541869.UgdfUgWYNB@mexican> (raw)
In-Reply-To: <1393015286.6771.110.camel@pasglop>
On Sat, 22 Feb 2014 07:41:26 Benjamin Herrenschmidt wrote:
> On Fri, 2014-02-21 at 15:33 +0100, Arnd Bergmann wrote:
[...]
>
> Should we (provided it's possible in HW) create two ranges instead ? One
> covering RAM and one covering MSIs ? To avoid stray DMAs whacking random
> HW registers in the chip ...
>
The thought occurred to me but I figured if we had stray DMAs then they could
already whack random bits of system memory which would likely break your
system anyway so I wasn't sure how much we'd gain. I guess whacking random HW
registers is arguably a bit worse though.
I did a bit of digging into the HW documentation and it looks like it _may_ be
possible to create a second range that would limit access to a subset of HW
registers, although there doesn't seem to be much flexibility. Personally I'm
not sure it justifies the work, but I'm happy to look into it a bit more if
you feel it's important?
- Alistair
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WARNING: multiple messages have this Message-ID (diff)
From: Alistair Popple <alistair@popple.id.au>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 7/7] powerpc: Added PCI MSI support using the HSTA module
Date: Tue, 25 Feb 2014 16:54:58 +1100 [thread overview]
Message-ID: <1541869.UgdfUgWYNB@mexican> (raw)
In-Reply-To: <1393015286.6771.110.camel@pasglop>
On Sat, 22 Feb 2014 07:41:26 Benjamin Herrenschmidt wrote:
> On Fri, 2014-02-21 at 15:33 +0100, Arnd Bergmann wrote:
[...]
>
> Should we (provided it's possible in HW) create two ranges instead ? One
> covering RAM and one covering MSIs ? To avoid stray DMAs whacking random
> HW registers in the chip ...
>
The thought occurred to me but I figured if we had stray DMAs then they could
already whack random bits of system memory which would likely break your
system anyway so I wasn't sure how much we'd gain. I guess whacking random HW
registers is arguably a bit worse though.
I did a bit of digging into the HW documentation and it looks like it _may_ be
possible to create a second range that would limit access to a subset of HW
registers, although there doesn't seem to be much flexibility. Personally I'm
not sure it justifies the work, but I'm happy to look into it a bit more if
you feel it's important?
- Alistair
next prev parent reply other threads:[~2014-02-25 5:55 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-21 6:31 [PATCH 0/7] IBM Akebono/PPC476GTR Support Alistair Popple
2014-02-21 6:31 ` Alistair Popple
2014-02-21 6:31 ` Alistair Popple
2014-02-21 6:31 ` [PATCH 1/7] IBM Akebono: Add a SDHCI platform driver Alistair Popple
2014-02-21 6:31 ` Alistair Popple
2014-02-21 6:31 ` Alistair Popple
[not found] ` <1392964293-13687-2-git-send-email-alistair-Y4h6yKqj69EXC2x5gXVKYQ@public.gmane.org>
2014-02-21 14:14 ` Arnd Bergmann
2014-02-21 14:14 ` Arnd Bergmann
2014-02-21 14:14 ` Arnd Bergmann
2014-02-24 0:38 ` Alistair Popple
2014-02-24 0:38 ` Alistair Popple
2014-02-21 6:31 ` [PATCH 2/7] IBM Akebono: Add support for a new PHY interface to the IBM emac driver Alistair Popple
2014-02-21 6:31 ` Alistair Popple
2014-02-21 6:31 ` Alistair Popple
2014-02-21 11:18 ` Mark Rutland
2014-02-21 11:18 ` Mark Rutland
2014-02-21 11:18 ` Mark Rutland
2014-02-24 2:09 ` Alistair Popple
2014-02-24 2:09 ` Alistair Popple
2014-02-24 2:09 ` Alistair Popple
2014-02-21 6:31 ` [PATCH 3/7] IBM Akebono: Add support to the OHCI platform driver for PPC476GTR Alistair Popple
2014-02-21 6:31 ` Alistair Popple
2014-02-21 6:31 ` Alistair Popple
2014-02-21 14:16 ` Arnd Bergmann
2014-02-21 14:16 ` Arnd Bergmann
2014-02-21 14:16 ` Arnd Bergmann
2014-02-24 0:20 ` Alistair Popple
2014-02-24 0:20 ` Alistair Popple
2014-02-24 0:20 ` Alistair Popple
2014-02-21 15:34 ` Alan Stern
2014-02-21 15:34 ` Alan Stern
2014-02-21 15:34 ` Alan Stern
2014-02-21 6:31 ` [PATCH 4/7] ECHI Platform: Merge ppc-of EHCI driver into the ehci-platform driver Alistair Popple
2014-02-21 6:31 ` Alistair Popple
2014-02-21 6:31 ` Alistair Popple
2014-02-21 11:48 ` Mark Rutland
2014-02-21 11:48 ` Mark Rutland
2014-02-21 11:48 ` Mark Rutland
2014-02-21 14:21 ` Arnd Bergmann
2014-02-21 14:21 ` Arnd Bergmann
2014-02-21 14:21 ` Arnd Bergmann
2014-02-22 2:32 ` Tony Prisk
2014-02-22 2:32 ` Tony Prisk
2014-02-22 2:32 ` Tony Prisk
2014-02-21 15:41 ` Alan Stern
2014-02-21 15:41 ` Alan Stern
2014-02-21 15:41 ` Alan Stern
2014-02-24 0:28 ` Alistair Popple
2014-02-24 0:28 ` Alistair Popple
2014-02-21 6:31 ` [PATCH 5/7] IBM Currituck: Clean up board specific code before adding Akebono code Alistair Popple
2014-02-21 6:31 ` Alistair Popple
2014-02-21 6:31 ` Alistair Popple
2014-02-21 6:31 ` [PATCH 6/7] IBM Akebono: Add the Akebono platform Alistair Popple
2014-02-21 6:31 ` Alistair Popple
2014-02-21 6:31 ` [PATCH 7/7] powerpc: Added PCI MSI support using the HSTA module Alistair Popple
2014-02-21 6:31 ` Alistair Popple
2014-02-21 6:31 ` Alistair Popple
2014-02-21 14:33 ` Arnd Bergmann
2014-02-21 14:33 ` Arnd Bergmann
2014-02-21 14:33 ` Arnd Bergmann
2014-02-21 20:41 ` Benjamin Herrenschmidt
2014-02-21 20:41 ` Benjamin Herrenschmidt
2014-02-21 20:41 ` Benjamin Herrenschmidt
2014-02-21 21:53 ` Arnd Bergmann
2014-02-21 21:53 ` Arnd Bergmann
2014-02-21 21:53 ` Arnd Bergmann
2014-02-25 5:54 ` Alistair Popple [this message]
2014-02-25 5:54 ` Alistair Popple
2014-02-25 5:54 ` Alistair Popple
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