From: Suprateeka R Hegde <hegdesmailbox@gmail.com>
To: "Jose E. Marchesi" <jose.marchesi@oracle.com>
Cc: "H.J. Lu" <hjl.tools@gmail.com>, gnu-gabi@sourceware.org
Subject: Re: RFC: Program Properties
Date: Fri, 01 Jan 2016 00:00:00 -0000 [thread overview]
Message-ID: <f8022fa9-2b42-25b4-9465-c6db743c23f2@gmail.com> (raw)
In-Reply-To: <87lgxspjho.fsf@oracle.com>
On 13-Oct-2016 05:07 PM, Jose E. Marchesi wrote:
>
> > 1. Minimum ISAs. Executables and shared objects, which are optimized
> > specifically to run on a particular processor, will not run on processors
> > which don't support the same set of ISAs. Since x86 only has EM_IAMCU,
> > EM_386 and EM_X86_64 ELF machine codes, run-time loader needs additional
> > information to tell if an executable or a shared object is compatible
> > with available ISAs.
>
> Why cant the following be defined as processor specific e_flags (like
> other processors do) in elf.h itself?
>
> It is easy to exhaust the space of EF_* flags. In sparc this happened
> many years ago, so we had to start using the tags Tag_GNU_SPARC_HWCAPS
> and Tag_GNU_SPARC_HWCAPS2 to denote hardware capabilities.
Hmm. Looks reasonable. But I still have some points to ponder:
e_flags is processor specific and I thought each processor has its own
space. And e_flags is also 4 byte size (purpose is unsigned integer).
The proposed numbering scheme is already at 17 and 14 more left-shifts
left. It would be same as e_flags capacity.
In addition, we can have arch-version mask just like Intel Itanium,
MIPS, etc. Of course thats slightly expensive but gives more space. And
if we can add asserts in compilers/binutils to check the range of
e_flags to be within the mask, then we can make it efficient too.
Am I missing anything?/
--
Supra
next prev parent reply other threads:[~2016-10-13 16:37 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-01 0:00 H.J. Lu
2016-01-01 0:00 ` Suprateeka R Hegde
2016-01-01 0:00 ` Jose E. Marchesi
2016-01-01 0:00 ` Suprateeka R Hegde [this message]
2016-01-01 0:00 ` Jose E. Marchesi
2016-01-01 0:00 ` Suprateeka R Hegde
2016-01-01 0:00 ` Joseph Myers
2016-01-01 0:00 ` Carlos O'Donell
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` Maciej W. Rozycki
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` Nick Clifton
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` Suprateeka R Hegde
2016-01-01 0:00 ` Maciej W. Rozycki
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 H.J. Lu
2016-01-01 0:00 ` Suprateeka R Hegde
2016-01-01 0:00 H.J. Lu
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