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[0/7] ARM: preparation for multiplatform iop32x

Message ID 20190809162956.488941-1-arnd@arndb.de (mailing list archive)
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Series ARM: preparation for multiplatform iop32x | expand

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Arnd Bergmann Aug. 9, 2019, 4:29 p.m. UTC
I'm looking into converting some of the remaining ARMv5
platforms in arch/arm/ to work together in a single kernel
binary.

IOP32x seems to be a fairly easy target for multiplatform
by itself, but the way the plat-iop code interacts with
three generations of the code, and how the dma-adma driver
is configured at compile-time for each version gets in the
way.

I considered adding more indirection layers for those two,
but removing iop33x and iop13xx is much easier in comparison,
so this is the first approach I'm posting.

If we conclude that iop33x and iop13xx are indeed not used
any more, the remaining patches in this series are
straightforward. The actual multiplatform conversion also
requires changes to the irqchip driver that are not completely
mechanic, and we can discuss those after deciding what to do
with the first set.

Adding a few people to Cc that historically worked on IOP.

      Arnd

Arnd Bergmann (7):
  [RFC] ARM: remove Intel iop33x and iop13xx support
  dma: iop-adma: include prefetch.h
  dma: iop-adma: use correct printk format strings
  dma: iop-adma: allow building without platform headers
  ARM: xscale: fix multi-cpu compilation
  ARM: iop32x: make mach/uncompress.h independent of mach/hardware.h
  ARM: iop32x: merge everything into mach-iop32x/

 arch/arm/Kconfig                              |   30 -
 arch/arm/Kconfig.debug                        |    8 +-
 arch/arm/Makefile                             |    3 -
 arch/arm/configs/iop13xx_defconfig            |  118 --
 arch/arm/configs/iop33x_defconfig             |   85 --
 arch/arm/mach-iop13xx/Kconfig                 |   21 -
 arch/arm/mach-iop13xx/Makefile                |    9 -
 arch/arm/mach-iop13xx/Makefile.boot           |    4 -
 arch/arm/mach-iop13xx/include/mach/adma.h     |  608 ---------
 .../mach-iop13xx/include/mach/entry-macro.S   |   29 -
 arch/arm/mach-iop13xx/include/mach/hardware.h |   22 -
 arch/arm/mach-iop13xx/include/mach/iop13xx.h  |  508 --------
 arch/arm/mach-iop13xx/include/mach/iq81340.h  |   29 -
 arch/arm/mach-iop13xx/include/mach/irqs.h     |  195 ---
 arch/arm/mach-iop13xx/include/mach/time.h     |  127 --
 .../mach-iop13xx/include/mach/uncompress.h    |   23 -
 arch/arm/mach-iop13xx/io.c                    |   77 --
 arch/arm/mach-iop13xx/iq81340mc.c             |   84 --
 arch/arm/mach-iop13xx/iq81340sc.c             |   86 --
 arch/arm/mach-iop13xx/irq.c                   |  227 ----
 arch/arm/mach-iop13xx/msi.c                   |  152 ---
 arch/arm/mach-iop13xx/msi.h                   |   12 -
 arch/arm/mach-iop13xx/pci.c                   | 1115 -----------------
 arch/arm/mach-iop13xx/pci.h                   |   66 -
 arch/arm/mach-iop13xx/setup.c                 |  595 ---------
 arch/arm/mach-iop13xx/tpmi.c                  |  244 ----
 arch/arm/mach-iop32x/Makefile                 |   10 +-
 arch/arm/{plat-iop => mach-iop32x}/adma.c     |   39 +-
 arch/arm/{plat-iop => mach-iop32x}/cp6.c      |    0
 arch/arm/mach-iop32x/em7210.c                 |    5 +-
 arch/arm/mach-iop32x/glantank.c               |    5 +-
 .../mach-iop32x/{include/mach => }/glantank.h |    2 -
 .../mach-iop32x/{include/mach => }/hardware.h |    6 +-
 arch/arm/{plat-iop => mach-iop32x}/i2c.c      |   21 +-
 arch/arm/mach-iop32x/include/mach/adma.h      |    6 -
 .../mach-iop32x/include/mach/entry-macro.S    |    2 -
 arch/arm/mach-iop32x/include/mach/iop32x.h    |   31 -
 arch/arm/mach-iop32x/include/mach/irqs.h      |   33 -
 arch/arm/mach-iop32x/include/mach/time.h      |    5 -
 .../arm/mach-iop32x/include/mach/uncompress.h |   18 +-
 .../asm/hardware => mach-iop32x}/iop3xx.h     |   18 +-
 arch/arm/mach-iop32x/iq31244.c                |    5 +-
 .../mach-iop32x/{include/mach => }/iq31244.h  |    2 -
 arch/arm/mach-iop32x/iq80321.c                |    5 +-
 .../mach-iop32x/{include/mach => }/iq80321.h  |    2 -
 arch/arm/mach-iop32x/irq.c                    |    3 +-
 arch/arm/mach-iop32x/irqs.h                   |   42 +
 arch/arm/mach-iop32x/n2100.c                  |    5 +-
 .../mach-iop32x/{include/mach => }/n2100.h    |    2 -
 arch/arm/{plat-iop => mach-iop32x}/pci.c      |    4 +-
 arch/arm/{plat-iop => mach-iop32x}/pmu.c      |    8 +-
 arch/arm/{plat-iop => mach-iop32x}/restart.c  |    4 +-
 arch/arm/{plat-iop => mach-iop32x}/setup.c    |    2 +-
 arch/arm/{plat-iop => mach-iop32x}/time.c     |    7 +-
 arch/arm/mach-iop33x/Kconfig                  |   22 -
 arch/arm/mach-iop33x/Makefile                 |    9 -
 arch/arm/mach-iop33x/Makefile.boot            |    4 -
 arch/arm/mach-iop33x/include/mach/adma.h      |    6 -
 .../mach-iop33x/include/mach/entry-macro.S    |   34 -
 arch/arm/mach-iop33x/include/mach/hardware.h  |   44 -
 arch/arm/mach-iop33x/include/mach/iop33x.h    |   37 -
 arch/arm/mach-iop33x/include/mach/iq80331.h   |   17 -
 arch/arm/mach-iop33x/include/mach/iq80332.h   |   17 -
 arch/arm/mach-iop33x/include/mach/irqs.h      |   57 -
 arch/arm/mach-iop33x/include/mach/time.h      |    5 -
 .../arm/mach-iop33x/include/mach/uncompress.h |   37 -
 arch/arm/mach-iop33x/iq80331.c                |  148 ---
 arch/arm/mach-iop33x/iq80332.c                |  148 ---
 arch/arm/mach-iop33x/irq.c                    |  115 --
 arch/arm/mach-iop33x/uart.c                   |  100 --
 arch/arm/mm/copypage-xscale.c                 |    6 +-
 arch/arm/plat-iop/Makefile                    |   28 -
 drivers/dma/Kconfig                           |    4 +-
 drivers/dma/iop-adma.c                        |   22 +-
 .../iop3xx-adma.h => drivers/dma/iop-adma.h   |    7 +-
 drivers/gpio/Kconfig                          |    2 +-
 drivers/i2c/busses/Kconfig                    |    2 +-
 .../linux/platform_data/dma-iop32x.h          |    4 +
 78 files changed, 134 insertions(+), 5510 deletions(-)
 delete mode 100644 arch/arm/configs/iop13xx_defconfig
 delete mode 100644 arch/arm/configs/iop33x_defconfig
 delete mode 100644 arch/arm/mach-iop13xx/Kconfig
 delete mode 100644 arch/arm/mach-iop13xx/Makefile
 delete mode 100644 arch/arm/mach-iop13xx/Makefile.boot
 delete mode 100644 arch/arm/mach-iop13xx/include/mach/adma.h
 delete mode 100644 arch/arm/mach-iop13xx/include/mach/entry-macro.S
 delete mode 100644 arch/arm/mach-iop13xx/include/mach/hardware.h
 delete mode 100644 arch/arm/mach-iop13xx/include/mach/iop13xx.h
 delete mode 100644 arch/arm/mach-iop13xx/include/mach/iq81340.h
 delete mode 100644 arch/arm/mach-iop13xx/include/mach/irqs.h
 delete mode 100644 arch/arm/mach-iop13xx/include/mach/time.h
 delete mode 100644 arch/arm/mach-iop13xx/include/mach/uncompress.h
 delete mode 100644 arch/arm/mach-iop13xx/io.c
 delete mode 100644 arch/arm/mach-iop13xx/iq81340mc.c
 delete mode 100644 arch/arm/mach-iop13xx/iq81340sc.c
 delete mode 100644 arch/arm/mach-iop13xx/irq.c
 delete mode 100644 arch/arm/mach-iop13xx/msi.c
 delete mode 100644 arch/arm/mach-iop13xx/msi.h
 delete mode 100644 arch/arm/mach-iop13xx/pci.c
 delete mode 100644 arch/arm/mach-iop13xx/pci.h
 delete mode 100644 arch/arm/mach-iop13xx/setup.c
 delete mode 100644 arch/arm/mach-iop13xx/tpmi.c
 rename arch/arm/{plat-iop => mach-iop32x}/adma.c (75%)
 rename arch/arm/{plat-iop => mach-iop32x}/cp6.c (100%)
 rename arch/arm/mach-iop32x/{include/mach => }/glantank.h (78%)
 rename arch/arm/mach-iop32x/{include/mach => }/hardware.h (90%)
 rename arch/arm/{plat-iop => mach-iop32x}/i2c.c (81%)
 delete mode 100644 arch/arm/mach-iop32x/include/mach/adma.h
 delete mode 100644 arch/arm/mach-iop32x/include/mach/iop32x.h
 delete mode 100644 arch/arm/mach-iop32x/include/mach/time.h
 rename arch/arm/{include/asm/hardware => mach-iop32x}/iop3xx.h (96%)
 rename arch/arm/mach-iop32x/{include/mach => }/iq31244.h (89%)
 rename arch/arm/mach-iop32x/{include/mach => }/iq80321.h (89%)
 create mode 100644 arch/arm/mach-iop32x/irqs.h
 rename arch/arm/mach-iop32x/{include/mach => }/n2100.h (89%)
 rename arch/arm/{plat-iop => mach-iop32x}/pci.c (99%)
 rename arch/arm/{plat-iop => mach-iop32x}/pmu.c (79%)
 rename arch/arm/{plat-iop => mach-iop32x}/restart.c (82%)
 rename arch/arm/{plat-iop => mach-iop32x}/setup.c (95%)
 rename arch/arm/{plat-iop => mach-iop32x}/time.c (97%)
 delete mode 100644 arch/arm/mach-iop33x/Kconfig
 delete mode 100644 arch/arm/mach-iop33x/Makefile
 delete mode 100644 arch/arm/mach-iop33x/Makefile.boot
 delete mode 100644 arch/arm/mach-iop33x/include/mach/adma.h
 delete mode 100644 arch/arm/mach-iop33x/include/mach/entry-macro.S
 delete mode 100644 arch/arm/mach-iop33x/include/mach/hardware.h
 delete mode 100644 arch/arm/mach-iop33x/include/mach/iop33x.h
 delete mode 100644 arch/arm/mach-iop33x/include/mach/iq80331.h
 delete mode 100644 arch/arm/mach-iop33x/include/mach/iq80332.h
 delete mode 100644 arch/arm/mach-iop33x/include/mach/irqs.h
 delete mode 100644 arch/arm/mach-iop33x/include/mach/time.h
 delete mode 100644 arch/arm/mach-iop33x/include/mach/uncompress.h
 delete mode 100644 arch/arm/mach-iop33x/iq80331.c
 delete mode 100644 arch/arm/mach-iop33x/iq80332.c
 delete mode 100644 arch/arm/mach-iop33x/irq.c
 delete mode 100644 arch/arm/mach-iop33x/uart.c
 delete mode 100644 arch/arm/plat-iop/Makefile
 rename arch/arm/include/asm/hardware/iop3xx-adma.h => drivers/dma/iop-adma.h (99%)
 rename arch/arm/include/asm/hardware/iop_adma.h => include/linux/platform_data/dma-iop32x.h (98%)

Comments

Lennert Buytenhek Aug. 9, 2019, 4:38 p.m. UTC | #1
On Fri, Aug 09, 2019 at 06:29:41PM +0200, Arnd Bergmann wrote:

> I'm looking into converting some of the remaining ARMv5
> platforms in arch/arm/ to work together in a single kernel
> binary.
> 
> IOP32x seems to be a fairly easy target for multiplatform
> by itself, but the way the plat-iop code interacts with
> three generations of the code, and how the dma-adma driver
> is configured at compile-time for each version gets in the
> way.
> 
> I considered adding more indirection layers for those two,
> but removing iop33x and iop13xx is much easier in comparison,
> so this is the first approach I'm posting.
> 
> If we conclude that iop33x and iop13xx are indeed not used
> any more, the remaining patches in this series are
> straightforward. The actual multiplatform conversion also
> requires changes to the irqchip driver that are not completely
> mechanic, and we can discuss those after deciding what to do
> with the first set.
> 
> Adding a few people to Cc that historically worked on IOP.

I haven't worked with any of these platforms for many years now,
and I can't really say much about their current use.
Wolfram Sang Aug. 9, 2019, 4:57 p.m. UTC | #2
On Fri, Aug 09, 2019 at 06:33:15PM +0200, Arnd Bergmann wrote:
> There are three families of IOP machines we support in Linux: iop32x
> (which includes EP80219), iop33x and iop13xx (aka IOP34x aka WP8134x).
> 
> All products we support in the kernel are based on the first of these,
> iop32x, the other families only ever supported the Intel reference
> boards but no actual machine anyone could ever buy.
> 
> While one could clearly make them all three work in a single kernel
> with some work, this takes the easy way out, removing the later two
> platforms entirely, under the assumption that there are no remaining
> users.
> 
> Earlier versions of OpenWRT and Debian both had support for iop32x
> but not the others, and they both dropped iop32x as well in their 2015
> releases.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Acked-by: Wolfram Sang <wsa@the-dreams.de> # for I2C parts
Dan Williams Aug. 9, 2019, 6:34 p.m. UTC | #3
[ add Martin (if cyrius.com address is still valid) ]

On Fri, Aug 9, 2019 at 9:35 AM Arnd Bergmann <arnd@arndb.de> wrote:
>
> There are three families of IOP machines we support in Linux: iop32x
> (which includes EP80219), iop33x and iop13xx (aka IOP34x aka WP8134x).
>
> All products we support in the kernel are based on the first of these,
> iop32x, the other families only ever supported the Intel reference
> boards but no actual machine anyone could ever buy.
>
> While one could clearly make them all three work in a single kernel
> with some work, this takes the easy way out, removing the later two
> platforms entirely, under the assumption that there are no remaining
> users.
>
> Earlier versions of OpenWRT and Debian both had support for iop32x
> but not the others, and they both dropped iop32x as well in their 2015
> releases.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> I'm just guessing that iop32x is still needed, and the other two are
> not. If anyone disagrees with that assessment, let me know so we
> can come up with an alternative approach.

I'm not sure who would scream if iop32x support went away as well, but
I have not followed this space in years hence copying Martin.

In any event:

Acked-by: Dan Williams <dan.j.williams@intel.com>
Russell King (Oracle) Aug. 9, 2019, 6:36 p.m. UTC | #4
On Fri, Aug 09, 2019 at 11:34:12AM -0700, Dan Williams wrote:
> [ add Martin (if cyrius.com address is still valid) ]
> 
> On Fri, Aug 9, 2019 at 9:35 AM Arnd Bergmann <arnd@arndb.de> wrote:
> >
> > There are three families of IOP machines we support in Linux: iop32x
> > (which includes EP80219), iop33x and iop13xx (aka IOP34x aka WP8134x).
> >
> > All products we support in the kernel are based on the first of these,
> > iop32x, the other families only ever supported the Intel reference
> > boards but no actual machine anyone could ever buy.
> >
> > While one could clearly make them all three work in a single kernel
> > with some work, this takes the easy way out, removing the later two
> > platforms entirely, under the assumption that there are no remaining
> > users.
> >
> > Earlier versions of OpenWRT and Debian both had support for iop32x
> > but not the others, and they both dropped iop32x as well in their 2015
> > releases.
> >
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> > I'm just guessing that iop32x is still needed, and the other two are
> > not. If anyone disagrees with that assessment, let me know so we
> > can come up with an alternative approach.
> 
> I'm not sure who would scream if iop32x support went away as well, but
> I have not followed this space in years hence copying Martin.
> 
> In any event:
> 
> Acked-by: Dan Williams <dan.j.williams@intel.com>

Those of us who have and still run Thecus N2100's, for example?
Dan Williams Aug. 9, 2019, 7:43 p.m. UTC | #5
On Fri, Aug 9, 2019 at 11:37 AM Russell King - ARM Linux admin
<linux@armlinux.org.uk> wrote:
>
> On Fri, Aug 09, 2019 at 11:34:12AM -0700, Dan Williams wrote:
> > [ add Martin (if cyrius.com address is still valid) ]
> >
> > On Fri, Aug 9, 2019 at 9:35 AM Arnd Bergmann <arnd@arndb.de> wrote:
> > >
> > > There are three families of IOP machines we support in Linux: iop32x
> > > (which includes EP80219), iop33x and iop13xx (aka IOP34x aka WP8134x).
> > >
> > > All products we support in the kernel are based on the first of these,
> > > iop32x, the other families only ever supported the Intel reference
> > > boards but no actual machine anyone could ever buy.
> > >
> > > While one could clearly make them all three work in a single kernel
> > > with some work, this takes the easy way out, removing the later two
> > > platforms entirely, under the assumption that there are no remaining
> > > users.
> > >
> > > Earlier versions of OpenWRT and Debian both had support for iop32x
> > > but not the others, and they both dropped iop32x as well in their 2015
> > > releases.
> > >
> > > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > > ---
> > > I'm just guessing that iop32x is still needed, and the other two are
> > > not. If anyone disagrees with that assessment, let me know so we
> > > can come up with an alternative approach.
> >
> > I'm not sure who would scream if iop32x support went away as well, but
> > I have not followed this space in years hence copying Martin.
> >
> > In any event:
> >
> > Acked-by: Dan Williams <dan.j.williams@intel.com>
>
> Those of us who have and still run Thecus N2100's, for example?

Nice! Good to hear.
Martin Michlmayr Aug. 12, 2019, 9:44 a.m. UTC | #6
* Dan Williams <dan.j.williams@intel.com> [2019-08-09 11:34]:
> > Earlier versions of OpenWRT and Debian both had support for iop32x
> > but not the others, and they both dropped iop32x as well in their 2015
> > releases.
> >
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> > I'm just guessing that iop32x is still needed, and the other two are
> > not. If anyone disagrees with that assessment, let me know so we
> > can come up with an alternative approach.
> 
> I'm not sure who would scream if iop32x support went away as well, but
> I have not followed this space in years hence copying Martin.

I believe iop13xx were mostly Intel dev boards.  I'm not aware of any
major devices based on iop33x.

As Arnd points out, Debian used to have support for various iop32x
devices.  While Debian hasn't supported iop32x in a number of years,
these devices are still usable and in use (RMK being a prime example).

So I think it's safe to drop iop33x/iop13xx while retaining support
for iop32x.

As I was looking at my email archives, I saw an email from Peter
Teichmann who was working on an iop33x based platform (around 2009) so
I've copied him as well.

> In any event:
> 
> Acked-by: Dan Williams <dan.j.williams@intel.com>

Acked-by: Martin Michlmayr <tbm@cyrius.com>
Linus Walleij Aug. 14, 2019, 8:36 a.m. UTC | #7
On Mon, Aug 12, 2019 at 11:45 AM Martin Michlmayr <tbm@cyrius.com> wrote:

> As Arnd points out, Debian used to have support for various iop32x
> devices.  While Debian hasn't supported iop32x in a number of years,
> these devices are still usable and in use (RMK being a prime example).

I suppose it could be a good idea to add support for iop32x to
OpenWrt and/or OpenEmbedded, both of which support some
pretty constrained systems. I am personally using these
distributions to support elder ARM hardware these days.

Just my €0.01
Linus Walleij
Arnd Bergmann Aug. 14, 2019, 10:48 a.m. UTC | #8
On Wed, Aug 14, 2019 at 10:36 AM Linus Walleij <linus.walleij@linaro.org> wrote:
>
> On Mon, Aug 12, 2019 at 11:45 AM Martin Michlmayr <tbm@cyrius.com> wrote:
>
> > As Arnd points out, Debian used to have support for various iop32x
> > devices.  While Debian hasn't supported iop32x in a number of years,
> > these devices are still usable and in use (RMK being a prime example).
>
> I suppose it could be a good idea to add support for iop32x to
> OpenWrt and/or OpenEmbedded, both of which support some
> pretty constrained systems. I am personally using these
> distributions to support elder ARM hardware these days.

OpenWRT also had support in the past and dropped it around the
same time as Debian. The way I understand it, a couple of platforms
including iop32x were moved out of the main openwrt source tree
into https://github.com/openwrt/targets/ because there was little
interest in keeping them running.

The idea was that any remaining users could add that feed to get
minimal support, but I'm not sure if would still work. In particular,
iop33x appears to be based on linux-3.3 plus three patches that
are no longer needed in mainline. Building a mainline kernel without
those patches may or may not work.

        Arnd
Arnd Bergmann Aug. 15, 2019, 12:50 p.m. UTC | #9
On Fri, Aug 9, 2019 at 6:30 PM Arnd Bergmann <arnd@arndb.de> wrote:
>
> I'm looking into converting some of the remaining ARMv5
> platforms in arch/arm/ to work together in a single kernel
> binary.
>
> IOP32x seems to be a fairly easy target for multiplatform
> by itself, but the way the plat-iop code interacts with
> three generations of the code, and how the dma-adma driver
> is configured at compile-time for each version gets in the
> way.
>
> I considered adding more indirection layers for those two,
> but removing iop33x and iop13xx is much easier in comparison,
> so this is the first approach I'm posting.
>
> If we conclude that iop33x and iop13xx are indeed not used
> any more, the remaining patches in this series are
> straightforward. The actual multiplatform conversion also
> requires changes to the irqchip driver that are not completely
> mechanic, and we can discuss those after deciding what to do
> with the first set.
>
> Adding a few people to Cc that historically worked on IOP.

I applied the IOP series to to the arm/soc branch now,
thanks for the reviews!

      Arnd
Aaro Koskinen Aug. 16, 2019, 3:42 p.m. UTC | #10
Hi,

On Wed, Aug 14, 2019 at 10:36:01AM +0200, Linus Walleij wrote:
> On Mon, Aug 12, 2019 at 11:45 AM Martin Michlmayr <tbm@cyrius.com> wrote:
> > As Arnd points out, Debian used to have support for various iop32x
> > devices.  While Debian hasn't supported iop32x in a number of years,
> > these devices are still usable and in use (RMK being a prime example).
> 
> I suppose it could be a good idea to add support for iop32x to
> OpenWrt and/or OpenEmbedded, both of which support some
> pretty constrained systems.

This platform is not really too constrained... E.g. on N2100 you have
512 MB RAM, SATA disks and gigabit ethernet. Not that different from
mvebu that Debian currently (?) supports. Maybe with multiplatform they
could support iop32x again.

A.
Russell King (Oracle) Aug. 16, 2019, 3:58 p.m. UTC | #11
On Fri, Aug 16, 2019 at 06:42:49PM +0300, Aaro Koskinen wrote:
> Hi,
> 
> On Wed, Aug 14, 2019 at 10:36:01AM +0200, Linus Walleij wrote:
> > On Mon, Aug 12, 2019 at 11:45 AM Martin Michlmayr <tbm@cyrius.com> wrote:
> > > As Arnd points out, Debian used to have support for various iop32x
> > > devices.  While Debian hasn't supported iop32x in a number of years,
> > > these devices are still usable and in use (RMK being a prime example).
> > 
> > I suppose it could be a good idea to add support for iop32x to
> > OpenWrt and/or OpenEmbedded, both of which support some
> > pretty constrained systems.
> 
> This platform is not really too constrained... E.g. on N2100 you have
> 512 MB RAM, SATA disks and gigabit ethernet. Not that different from
> mvebu that Debian currently (?) supports. Maybe with multiplatform they
> could support iop32x again.

Probably not.  The kernel has a dividing line between ARMv5 and ARMv6
where it's not possible to multiplatform across that boundary, so
you're already needing separate kernel images there.

Secondly, armhf distros won't be compatible with ARMv5, and to make
them compatible will make performance on armhf suffer - you have to
stop using barriers, exclusive load/store and a few other things.
You have to rely on the kuser page exported by the kernel (which is
now optional as it's deemed to be a security issue for ROP attacks)
for some things that such a userspace requires - such as NPTL support.

Effectively, ARMv5 is an entirely separate userspace distro from armhf.
Aaro Koskinen Aug. 16, 2019, 4:15 p.m. UTC | #12
Hi,

On Fri, Aug 16, 2019 at 04:58:33PM +0100, Russell King - ARM Linux admin wrote:
> On Fri, Aug 16, 2019 at 06:42:49PM +0300, Aaro Koskinen wrote:
> > On Wed, Aug 14, 2019 at 10:36:01AM +0200, Linus Walleij wrote:
> > > On Mon, Aug 12, 2019 at 11:45 AM Martin Michlmayr <tbm@cyrius.com> wrote:
> > > > As Arnd points out, Debian used to have support for various iop32x
> > > > devices.  While Debian hasn't supported iop32x in a number of years,
> > > > these devices are still usable and in use (RMK being a prime example).
> > > 
> > > I suppose it could be a good idea to add support for iop32x to
> > > OpenWrt and/or OpenEmbedded, both of which support some
> > > pretty constrained systems.
> > 
> > This platform is not really too constrained... E.g. on N2100 you have
> > 512 MB RAM, SATA disks and gigabit ethernet. Not that different from
> > mvebu that Debian currently (?) supports. Maybe with multiplatform they
> > could support iop32x again.
> 
> Probably not.  The kernel has a dividing line between ARMv5 and ARMv6
> where it's not possible to multiplatform across that boundary, so
> you're already needing separate kernel images there.
> 
> Secondly, armhf distros won't be compatible with ARMv5, and to make
> them compatible will make performance on armhf suffer - you have to
> stop using barriers, exclusive load/store and a few other things.
> You have to rely on the kuser page exported by the kernel (which is
> now optional as it's deemed to be a security issue for ROP attacks)
> for some things that such a userspace requires - such as NPTL support.
> 
> Effectively, ARMv5 is an entirely separate userspace distro from armhf.

I thought they still had armel for ARMv5 and mvebu (kirkwood).

A.