From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: VANDROVE@vc.cvut.cz (Petr Vandrovec)
Cc: rmk@arm.linux.org.uk (Russell King), linux-kernel@vger.kernel.org
Subject: Re: Physical memory addresses/PCI memory addresses/io_remap
Date: Thu, 14 Dec 2000 18:37:22 +0000 (GMT) [thread overview]
Message-ID: <E146dFr-00009D-00@the-village.bc.nu> (raw)
In-Reply-To: <FA894952830@vcnet.vc.cvut.cz> from "Petr Vandrovec" at Dec 14, 2000 05:56:54 PM
> > 1. Should pci_resource_start be returning the PCI memory space address or
> > a physical memory space address?
>
> I believe that pci_resource_start() should return physical address, not
> bus one. It already happens on PReP.
It returns a cookie for use with ioremap. Who says that a given device has
a constant bus or physical mapping that is unique ?
> > 4. What does this mean for ioremap? (currently, on ARM, ioremap takes
> > PCI memory space addresses, not a physical memory address, which makes
> > the physmap MTD driver technically broken).
>
> And ioremap() should take physical address, returning virtual one.
No. Ioremap takes a cookie and returns a different cookie suitable for using
with readb/writeb/memcpy_fromio and friends.
Eg on Sparc64 its a physical address and readb uses TLB bypass
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prev parent reply other threads:[~2000-12-14 19:05 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-12-14 17:56 Petr Vandrovec
2000-12-14 18:37 ` Alan Cox [this message]
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