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Re: PATCH: Don't align text/data/bss sections in x86 assembler
- From: John Reiser <jreiser at bitwagon dot com>
- To: binutils at sourceware dot org
- Date: Mon, 03 Jun 2013 09:28:09 -0700
- Subject: Re: PATCH: Don't align text/data/bss sections in x86 assembler
- References: <20130531173241 dot GA30259 at intel dot com> <51AC6EFE02000078000DA75F at nat28 dot tlf dot novell dot com> <CAMe9rOpNY_h4CSnf1Wnkr-aqd3ExUHmFwxXR7AQ4NK8boNsXPQ at mail dot gmail dot com>
On 06/03/2013, H.J. Lu wrote:
> [[snip]] The section
> alignment is very arbitrary:
>
> 1. Many arches don't do it.
> 2. Only x86 ELF did it.
x86 ELF did it for a reason. The default addressing convention for 16-bit sections
(i286) requires paragraph alignment which in hardware is at least 0x10
but in UNIX traditionally was 0x20. Embedding 16-bit code at the beginning
of a 32-bit .text section was reasonable and did happen. Recent Linux
no longer supports virtual86 mode, but there are other OS.
> 3. It only aligned text/data/bss sections and there are many
> other sections with code and data which aren't aligned.
> 4. Neither gABI nor psABI require it.
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