From: David Laight <David.Laight@ACULAB.COM>
To: 'Russell King - ARM Linux admin' <linux@armlinux.org.uk>,
Ansuel Smith <ansuelsmth@gmail.com>
Cc: "stable@vger.kernel.org" <stable@vger.kernel.org>,
Palmer Dabbelt <palmerdabbelt@google.com>,
Luis Chamberlain <mcgrof@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [RESEND PATCH] arm: Enlarge IO_SPACE_LIMIT needed for some SoC
Date: Sun, 9 May 2021 16:54:51 +0000 [thread overview]
Message-ID: <4f6e5115e00e4df2a84a57ed0359e907@AcuMS.aculab.com> (raw)
In-Reply-To: <20210509130956.GI1336@shell.armlinux.org.uk>
...
> Well, an obvious question would be: do you really need that much IO
> space? PCs have got away with 64K of IO space without having a problem
> for years, so 64K per bus should be fine. If you have 3 buses, that
> should be 3 * 64K or 192K.
Not only that, but most modern PCI (even) cards don't require IO space.
Or does this include memory space - which can be much bigger.
I have cut one of our FPGA PCIe slaves down from two 8MB BARs to
two 1MB ones, with the extra small BARs (eg for MSI-X) the bridge
would have allocated 32MB, now 4MB.
Fortunately that card only needs to work on x86-64.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
prev parent reply other threads:[~2021-05-09 16:55 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-08 17:55 Ansuel Smith
2021-05-08 18:50 ` Russell King - ARM Linux admin
2021-05-08 22:51 ` Ansuel Smith
2021-05-09 13:09 ` Russell King - ARM Linux admin
2021-05-09 16:54 ` David Laight [this message]
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