Re: shared memory problem on armel

[Mike Thompson <mpthompson@gmail.com>]

Ben,

With Raspbian, we've done our best to maintain maximum compatibility with Debian and deliver to the Raspberry Pi community a rich Debian experience to a million+ new Linux users.  As the decision for Armhf to support Armv7+ rather than Armv6 was made well before the Raspberry Pi existed we've done our best to lemons into lemonade and I think we've done a fairly good job.  Incompatibility related to Raspbian was an unfortunate necessity rather than a willful choice.  Packages built for Raspbian are 100% forwards compatible Debian armhf as they are compliant with the armhf ABI and armv7 is fully upwards compatible with armv6.  In my discussions with people when Raspbian was first being built, I believe this was the intent behind some of the decisions around the armhf ABI.

As armhf really describes the ABI rather than the underlying CPU architecture, it would make our jobs with Raspbian much easier if CPU architecture dependent packages could test that the architecture is indeed Armv7+ and not blindly assume armhf implicitly means the system is running on an Armv7+ architecture. It's unfortunate that a handful of packages make this assumption and adding more to the mix doesn't help.

Ideally, I would love to see Raspbian folded back into the Debian Project, but I realize this won't happen for a variety of reasons.  Therefore, it would be useful if at least those working on armhf packages realize that there are those dependent upon CPU architecture related decisions when packages are created.

I'll get off my soapbox in defense of Raspbian.  Thanks for listening.

Mike Thompson

On Thu, Feb 7, 2013 at 10:10 AM, Ben Hutchings <ben@decadent.org.uk> wrote:

On Thu, Feb 07, 2013 at 06:42:20PM +0100, martinwguy wrote:
> >> Mapping the same shared memory twice in one process is stupid, anyway.
> >> Just disable the test on armel and armhf.
> >
> > Correction: starting from ARMv7, this is supported.  So the test can be
> > enabled for armhf (and arm64).
>
> No, you have to test for the architecture being V7+, not for armhf.
> That armhf in Debian is V7+ is a coincidence (or, rather, a political
> choice, not a technical one).
> For example, the armv6 armhf port for the Raspberry Pi in armhf/V6.

The wilful incompatibility of Debian derivatives should not restrict
what Debian does.

Ben.

--
Ben Hutchings
We get into the habit of living before acquiring the habit of thinking.
                                                              - Albert Camus


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