From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Josh Boyer <jwboyer@gmail.com>
Cc: paulus@samba.org, linuxppc-dev@lists.ozlabs.org,
Ian Munsie <imunsie@au1.ibm.com>,
linux-kernel@vger.kernel.org
Subject: Re: Introduce support for little endian PowerPC
Date: Fri, 01 Oct 2010 22:21:32 +1000 [thread overview]
Message-ID: <1285935692.2463.84.camel@pasglop> (raw)
In-Reply-To: <AANLkTikHcoccu-WGtSOSdkwU6Tw_An_VFkUcEoY==8=c@mail.gmail.com>
On Fri, 2010-10-01 at 07:36 -0400, Josh Boyer wrote:
> On Fri, Oct 1, 2010 at 3:05 AM, Ian Munsie <imunsie@au1.ibm.com> wrote:
> > This patch set in combination with a patched GCC, binutils, uClibc and
> > buildroot has allowed for a full proof of concept little endian environment on
> > a 440 Taishan board, which was able to successfully run busybox, OpenSSH and a
> > handful of other userspace programs without problems.
>
> Aside from my general "uh, why?" stance, I'm very very hesitant to
> integrate anything in the kernel that doesn'.t have released patches
> on the toolchain side.
We aren't yet talking about merging that as-is, though I beleive at
least -some- of the patches have merit on their own, such as the proper
accessors for device-tree properties. At the very least, it would make
it less painful for archs like ARM to borrow code in that area and will
make it cleaner for sparse when we generalize endian annotations.
The toolchain work was done as a quick & dirty experiment. Whether some
"proper" work there will happen remains to be decided.
> Also, which uClibc? The old and crusty uClibc that uses the horrible
> linuxthreads, or the somewhat less crusty that just switched to NPTL
> (which hasn't been verified on normal PowerPC that I recall). Why not
> use glibc...
Because this was a proof of concept and as such, it was easier to deal
with uclibc initially to get busybox going :-)
> > This is not yet complete support for little endian PowerPC, some outstanding
> > issues that I am aware of are:
> > * We only support 32bit PowerPC for now (and indeed, only 44x)
> > * The vdso has not been fixed to be endian agnostic - any userspace program
> > accessing it will get an unexpected result.
> > * I have not touched PCI at all
> > * Remaining device tree accesses still need to be examined to ensure they are
> > correctly handling the endianess of the device tree.
> > * Any other driver that uses the device tree is likely be broken for the same reason.
> > * I've included a patch for the alignment handler, however it is as yet
> > completely untested due to a property of the hardware I've been using for
> > testing.
>
> I'm not meeting to detract here, but the Kconfig should be dependent
> on && BROKEN until the above is fixed.
Right.
I think Ian wasn't clear enough on the fact that those patches aren't
meant to be merged in the next merge window :-) I told him to shoot them
to the list for review, comments and discussions, but if we decide to
move along with integrating that, there's definitely more work to do.
Cheers,
Ben.
next prev parent reply other threads:[~2010-10-01 12:21 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-01 7:05 Introduce support for little endian PowerPC Ian Munsie
2010-10-01 7:05 ` [PATCH 01/18] powerpc: Add ability to build little endian kernels Ian Munsie
2010-10-01 9:18 ` Kumar Gala
2010-10-01 11:28 ` Josh Boyer
2010-10-01 12:09 ` Benjamin Herrenschmidt
2010-10-01 11:40 ` Josh Boyer
2010-10-01 12:22 ` Benjamin Herrenschmidt
2010-10-01 7:05 ` [PATCH 02/18] powerpc: Add CROSSBE_COMPILE to build big endian boot wrapper Ian Munsie
2010-10-01 7:13 ` Geert Uytterhoeven
2010-10-01 7:19 ` Ian Munsie
2010-10-01 7:05 ` [PATCH 03/18] powerpc: Support parsing a little endian kernel from zImage wrapper Ian Munsie
2010-10-01 7:05 ` [PATCH 04/18] powerpc: Allow taishan platform to boot a little endian kernel Ian Munsie
2010-10-01 7:05 ` [PATCH 05/18] powerpc: Wire up 44x little endian boot for remaining 44x targets Ian Munsie
2010-10-01 11:27 ` Josh Boyer
2010-10-06 1:28 ` Ian Munsie
2010-10-06 1:55 ` Josh Boyer
2010-10-06 2:10 ` Sean MacLennan
2010-10-01 7:05 ` [PATCH 06/18] powerpc 44x: Set E bit in TLBs and PTEs when CPU is in little endian mode Ian Munsie
2010-10-01 7:06 ` [PATCH 07/18] powerpc: Use generic bitops for little endian bitmap operations Ian Munsie
2010-10-01 7:06 ` [PATCH 08/18] powerpc: Include the appropriate endianness header Ian Munsie
2010-10-01 7:06 ` [PATCH 09/18] powerpc: Support device tree regardless of CPU endianness Ian Munsie
2010-10-03 3:15 ` Grant Likely
2010-10-03 6:22 ` Benjamin Herrenschmidt
2010-10-01 7:06 ` [PATCH 10/18] powerpc: Support endian agnostic MMIO Ian Munsie
2010-10-01 7:06 ` [PATCH 11/18] powerpc: Make assembly endian agnostic when accessing 64bit values Ian Munsie
2010-10-01 7:06 ` [PATCH 12/18] powerpc 44x: Handle TLB miss regardless of endianness Ian Munsie
2010-10-01 7:06 ` [PATCH 13/18] powerpc 44x: Make DCR endianness agnostic Ian Munsie
2010-10-01 7:06 ` [PATCH 14/18] powerpc, of_serial: Endianness issues setting up the serial ports Ian Munsie
2010-10-07 23:23 ` Grant Likely
2010-10-01 7:06 ` [PATCH 15/18] mtd: Fix endianness issues from device tree Ian Munsie
2010-10-01 19:29 ` Artem Bityutskiy
2010-10-01 7:06 ` [PATCH 16/18] powerpc: Fix endianness issues in alignment handler Ian Munsie
2010-10-01 7:06 ` [PATCH 17/18] net: Fix endianess issues in IBM newemac driver Ian Munsie
2010-10-01 7:06 ` [PATCH 18/18] powerpc: Fix jiffies variable on little endian Ian Munsie
2010-10-01 9:02 ` Introduce support for little endian PowerPC Kumar Gala
2010-10-01 11:30 ` Josh Boyer
2010-10-01 11:55 ` Gary Thomas
2010-10-01 12:15 ` Benjamin Herrenschmidt
2010-10-01 12:37 ` Gary Thomas
2010-10-01 12:14 ` Benjamin Herrenschmidt
2010-10-01 16:20 ` Michel Dänzer
2010-10-01 20:50 ` Benjamin Herrenschmidt
2010-10-04 10:30 ` Michel Dänzer
2010-10-04 22:50 ` Benjamin Herrenschmidt
2010-10-01 17:59 ` Kumar Gala
2010-10-01 20:51 ` Benjamin Herrenschmidt
2010-10-01 22:03 ` Olof Johansson
2010-10-01 22:28 ` Benjamin Herrenschmidt
2010-10-07 16:25 ` Hollis Blanchard
2010-10-01 11:36 ` Josh Boyer
2010-10-01 12:21 ` Benjamin Herrenschmidt [this message]
2010-10-06 1:04 ` Ian Munsie
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