On 05/24/14 11:23, Ian Lepore wrote:
On Sat, 2014-05-24 at 18:53 +0200, Tijl Coosemans wrote:
On Sat, 24 May 2014 09:04:33 -0700 Nathan Whitehorn wrote:
On 05/24/14 07:59, Tijl Coosemans wrote:
On Fri, 23 May 2014 17:29:48 -0600 Warner Losh wrote:
On May 23, 2014, at 10:20 AM, Baptiste Daroussin <b...@freebsd.org> wrote:
On Fri, May 23, 2014 at 08:52:28AM -0700, Nathan Whitehorn wrote:
On 05/23/14 08:36, Baptiste Daroussin wrote:
On Fri, May 23, 2014 at 08:19:34AM -0700, Nathan Whitehorn wrote:
Is there any chance of finally switching the pkg abi identifiers to just
be uname -p?
-Nathan
Keeping asking won't make it happen, I have explained a large number of time
why it
happened, why it is not easy for compatibility and why uname -p is still not
representing the ABI we do support, and what flexibility we need that the
current string offers to us.
if one is willing to do the work, please be my guess, just dig into the archives
and join the pkg development otherwise: no it won't happen before a while
because we have way too much work on the todo and this item is stored at the
very end of this todo.
regards,
Bapt
I'm happy to do the work, and have volunteered now many times. If uname
-p does not describe the ABI fully, then uname -p needs changes on the
relevant platforms. Which are they? What extra flexibility does the
string give you if uname -p describes the ABI completely?
-Nathan
just simple examples in armv6:
- eabi vs oabi
- The different float abi (even if only one is supported for now others are
being worked on)
- little endian vs big endian
All of those are encoded in the MACHINE_ARCH + freebsd version, no exceptions
on supported architectures that are tier 2 or higher. This seems like a weak
reason.
the extras flexibilit is being able to say this binary do support freebsd i386
and amd64 in one key, freebsd:9:x86:*, or or all arches freebsd:10:*
Will there be a program to convert this new, special invention to the standard
that we’ve used for the past 20 years? If you need the flexibility, which I’m
not
entirely sure I’ve seen a good use case for. When would you have a x86 binary
package? Wouldn’t it be either i386 or amd64?
ABI isn't just about the instruction set. It's also about the sizes of C
types (like pointers). If I remember correctly, the pkg scheme was chosen
to allow for ABIs like x32 which use the 64 bit instruction set with 32
bit pointers. MACHINE_ARCH would also be amd64 in this case.
No, it wouldn't. MACHINE_ARCH would be something else (x32, probably) in
such cases. MACHINE_ARCH (and uname -p, which reports it) is the FreeBSD
ABI identifier and encodes 100% of the ABI information. This would be
true even if there is never an x32 kernel.
No, there's no such thing as an x32 kernel. It's an amd64 kernel that
supports a second userland ABI. In C preprocessor terms they are
distinguished by (__amd64__ && _LP64) and (__amd64__ && !_LP64).
uname -p gives you the processor architecture (the __amd64__ bit) but
then you can still choose the sizes of standard C types (the _LP64 bit).
So far we've always had one ABI per processor architecture but this
is not strictly necessary.
All you have to do is look at the plethora of ARM ABIs we support (and
the corresponding separate kernel for each) to see the falseness of that
last sentence. ARM variations include v4 vs v6, OABI vs EABI (calling
and register usage standards), hard vs soft float, little vs big endian.
Virtually all combinations of those are possible (there are a few combos
we don't support), and each one has its own MACHINE_ARCH.
Exactly. This doesn't rely on the kernel either. The hw.machine_arch
sysctl (what uname -p returns) gives the ABI of the calling binary
rather than the kernel. So if you use a 32-bit uname (e.g. in a chroot)
on an amd64 host, you get i386. The same will be true if and when we
support a 32-bit amd64 userland -- even if there is no x32 kernel, an
x32 uname will return "x32" (or "amd32" or whatever it ends up being
called). That string will also appear in kern.supported_archs.
MACHINE_ARCH completely defines the ABI, without exception, because, as
a matter of policy, that's what we have defined it to mean. If there are
any circumstances where it does not -- and none have been offered so far
-- those are simply bugs that need fixing.
-Nathan
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