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Re: [EXTERNAL]Re: [PATCH v3] Mips support for PT_GNU_STACK


________________________________________
From: Joseph Myers <joseph@codesourcery.com>
Sent: Monday, August 5, 2019 9:25 PM
To: Dragan Mladjenovic
Cc: libc-alpha@sourceware.org; Carlos O'Donell; Adhemerval Zanella; Maciej W . Rozycki; Faraz Shahbazker
Subject: [EXTERNAL]Re: [PATCH v3] Mips support for PT_GNU_STACK

On Sun, 4 Aug 2019, Dragan Mladjenovic wrote:

> In order to allow for the tool-chain to safely use PT_GNU_STACK by
> default, this patch bumps the minimum kernel version to 4.8 for the
> hard-float builds done with GNU.stack enabled tool-chain.

I think this explanation needs expanding.  What is meant by "GNU.stack
enabled tool-chain"?  How do you control whether a toolchain you build is
such a toolchain or not?

  Yes, sorry about that.
  GCC proposal can be found at https://gcc.gnu.org/ml/gcc-patches/2019-08/msg00251.html.
  By "GNU.stack enabled tool-chain" I meant a toolchain whose gcc emits .note.GNU-stack by
  default, which none currently do.  Posted patch changes that if gcc is configured against next
  glibc release using --with-glibc-version. 

If simply building new-enough GCC and glibc quietly results in a new
kernel requirement without any special configure options being needed,
that could be a problem - we'd need to consider carefully whether such an
increase is desirable, or whether it's only appropriate given a suitable
--enable-kernel option.

  We could simply error out during the configure in this case and let the user
  set --enable-kernel if he wishes so, but I understand, it would be nice to allow
  it to opt out from that forcing the gibc to be build with executable stack.

  Will think about that.



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