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Re: g77 ordering of "COMMON A, IPAD" could cause crash on i386platforms
- From: "Zack Weinberg" <zack at codesourcery dot com>
- To: <aspiesrule at mcleodusa dot net>
- Cc: <gcc at gcc dot gnu dot org>
- Date: Mon, 03 Nov 2003 18:00:11 -0800
- Subject: Re: g77 ordering of "COMMON A, IPAD" could cause crash on i386platforms
<aspiesrule@mcleodusa.net> writes:
> If "COMMON A, IPAD" was compiled by g77 without proper padding
> for a 486 or higher IA-32 CPU, the AC flag in EFLAGS and the AM bit
> in CR0 were both set, the program was running at PL3, and the vector
> (interrupt gate descriptor) for the #AC exception was not
> initalized, trashed, or points to an object that cannot be executed
> or is garbage, the computer could do some strange things. Point: It
> is best to add proper padding, not only to reap its performance
> benefits, but to prevent unnecessary exceptions (or the potential
> for undefined behavior) on the i386, for example.
g77 is not responsible for the operating system having failed to
initialize the interrupt table properly.
Have you actually observed g77 fail to give an object proper
alignment, or are you speculating? If the former, please submit a
proper bug report with complete test case.
zw