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Bug 1152 - nasm-2.09 changed __OUTPUT_FORMAT__ derivation
Summary: nasm-2.09 changed __OUTPUT_FORMAT__ derivation
Status: RESOLVED FIXED
Alias: None
Product: SDL
Classification: Unclassified
Component: build (show other bugs)
Version: HG 1.2
Hardware: x86 Linux
: P2 normal
Assignee: Sam Lantinga
QA Contact: Sam Lantinga
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2011-02-24 09:36 UTC by Petr Pisar
Modified: 2011-02-24 09:41 UTC (History)
0 users

See Also:

Attachments
Fix (2.60 KB, patch)
2011-02-24 09:37 UTC, Petr Pisar 		Details | Diff
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Description Petr Pisar 2011-02-24 09:36:07 UTC 
While compiling SDL-1.2.14 with newer nasm (Hermes library in x86 assembler is embedded), I found the GNU-stack notice is missing resulting in library marked as requiring executable stack.

I discovered nasm-2.09 changed a way how output format argument (nasm -f elf) becomes a __OUTPUT_FORMAT__ macro used to conditionalize the GNU-stack section:

  %ifidn __OUTPUT_FORMAT__,elf
  section .note.GNU-stack noalloc noexec nowrite progbits
  %endif

Olde nasm defined __OUTPUT_FORMAT__ as `elf'. Version 2.09 defines it as `elf32' on x86:

  Short aliases \c{win}, \c{elf} and \c{macho} for output formats are
  introduced.  Each stands for \c{win32}, \c{elf32} and \c{macho32}
  accordingly.


Thus SDL compiled with newer nasm misses the section and linker assumes the stack is executable.
Comment 1 Petr Pisar 2011-02-24 09:37:56 UTC 
Created attachment 588 [details]
Fix

This patch changes the `elf' format to `elf32' (as the code is used on x86 only). It can be compiled with old and with new nasm successfully. Also I believe it still works with yasm, as it supports `elf32' format too.
Comment 2 Sam Lantinga 2011-02-24 09:41:47 UTC 
This fix is in, thanks!
http://hg.libsdl.org/SDL/rev/30e4d724fe98