Date: Thu, 23 Feb 2012 09:31:40 +1100
From: Stephen Rothwell <sfr@canb.auug.org.au>
To: Matt Fleming <matt@console-pimps.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
        Matt Fleming <matt.fleming@intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH] x86, efi: Fix unaligned access and endian issues
Message-Id: <20120223093140.3f8ad47252f9f331d355ea57@canb.auug.org.au>
In-Reply-To: <1329919208-8700-1-git-send-email-matt@console-pimps.org>
References: <1329919208-8700-1-git-send-email-matt@console-pimps.org>
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Hi Matt,

On Wed, 22 Feb 2012 14:00:08 +0000 Matt Fleming <matt@console-pimps.org> wr=
ote:
>
> From: Matt Fleming <matt.fleming@intel.com>
>=20
> We need to read from and write to 'buf' a byte at a time otherwise
> it's possible we'll perform an unaligned access, which can lead to a
> segfault when cross-building an x86 kernel on risc architectures.
>=20
> Also, we may need to convert the endianness of the data we read
> from/write to buf, so let's add some helper functions to do that.
>=20
> Stephen Rothwell noticed this bug when he hit a segfault while
> cross-building an x86_64 allmodconfig kernel on PowerPC.
>=20
> Cc: H. Peter Anvin <hpa@zytor.com>
> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> Signed-off-by: Matt Fleming <matt.fleming@intel.com>

Tested-by: Stephen Rothwell <sfr@canb.auug.org.au> (cross build only)

The bzImage from a ARCH=3Dx86_64 defconfig+CONFIG_EFI_STUB cross build is
in http://ozlabs.org/~sfr/bzImage if you want to attempt to boot it.

One little thing is that those two new functions may we warned about as
unused if CONFIG_EFI_STUB is not set (I have not done that build yet).

--=20
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au

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