From: David Hawkins <dwh@ovro•caltech.edu>
To: "Jenkins, Clive" <Clive.Jenkins@xerox•com>
Cc: linuxppc-embedded@ozlabs•org
Subject: Re: Yosemite/440EP why are readl()/ioread32() setup to readlittle-endian?
Date: Wed, 01 Feb 2006 12:35:33 -0800 [thread overview]
Message-ID: <43E11B95.9030902@ovro.caltech.edu> (raw)
In-Reply-To: <35786B99AB3FDC45A8215724617919736D921B@gbrwgceumf01.eu.xerox.net>
> I said this without looking up the example you cited.
> I agree now, the example is incorrect; and yes, file a bug
> report at oreilly!
Ok, I will.
> I think, from memory, that elsewhere in the book Rubini does
> say that readl()... are for the PCI bus, but cross-arch issues
> are only addressed in certain sections.
I didn't find anything that specifically mentioned their
use was for the PCI bus only. The endianness swapping
features of the pci_config_xxx functions are clearly
stated, but not the readl/writel. And of course the
example I refer to clearly uses those functions on the
PCI bus incorrectly.
But its still a great book.
> I always find out exactly what these macros do on the arch
> I am using, then I know where I stand. I find LXR (Google it if
> you don't know it) good for browsing the source of vanilla
> kernels. After finding out how and where it is done, I then
> double check the relevant files of the actual kernel I am using.
>
> ppc implementations of readl, writel, cpu_to_le32 use the byte-
> reversed load/store word instructions.
Ahh, very good advice. I think I read about LXR in one of
Freescale's app notes on porting Linux. I'll go take a look
on Google.
Thanks
Dave
next prev parent reply other threads:[~2006-02-01 20:33 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-01 18:35 Yosemite/440EP why are readl()/ioread32() setup to readlittle-endian? Jenkins, Clive
2006-02-01 20:35 ` David Hawkins [this message]
-- strict thread matches above, loose matches on Subject: below --
2006-02-02 9:35 Jenkins, Clive
2006-02-02 9:46 ` Eugene Surovegin
2006-02-02 14:37 ` Matt Porter
2006-02-02 17:45 ` Eugene Surovegin
2006-02-02 18:16 ` Matt Porter
2006-02-01 11:19 Jenkins, Clive
2006-02-01 17:02 ` David Hawkins
2006-02-01 17:44 ` Matt Porter
2006-02-01 17:53 ` David Hawkins
2006-02-01 18:04 ` David Hawkins
2006-02-01 18:11 ` Eugene Surovegin
2006-02-01 18:20 ` David Hawkins
2006-02-01 18:23 ` Eugene Surovegin
2006-02-01 21:14 ` Peter Korsgaard
2006-02-02 0:54 ` Kumar Gala
2006-02-02 3:07 ` Matt Porter
2006-02-02 8:09 ` Peter Korsgaard
2006-02-02 9:08 ` Eugene Surovegin
2006-02-02 17:34 ` Dale Farnsworth
2006-02-02 14:21 ` Matt Porter
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