From: Sam Ravnborg <sam@ravnborg.org>
To: linux arch <linux-arch@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Cc: Tim Abbott <tabbott@mit.edu>
Subject: Minimal linker script
Date: Sat, 9 May 2009 10:00:06 +0200 [thread overview]
Message-ID: <20090509080006.GA22617@uranus.ravnborg.org> (raw)
While trying to address the common patters in our
linker scripts I made a sketch of a minimal linker script.
As this will be the basis for my continued effort to create
a set of defines that can be used by all architectues I would like
to receive some feedback.
/*
* Helper macros to support writing architecture specific
* linker scripts.
*
* A minimal linker scripts has following content:
*
* OUTPUT_FORMAT(...)
* OUTPUT_ARCH(...)
* ENTRY(...)
* SECTIONS
* {
* . = START;
* __init_begin = .;
* HEAD_SECTION
* INIT_TEXT_SECTION(PAGE_SIZE)
* INIT_DATA_SECTION(...)
* PERCPU(PAGE_SIZE)
* __init_end = .;
*
* _stext = .;
* TEXT_SECTION = 0
* _etext = .;
*
* _sdata = .;
* RO_DATA_SECTION(PAGE_SIZE)
* RW_DATA_SECTION(...)
* _edata = .;
*
* EXCEPTION_TABLE(...)
* NOTES
*
* __bss_start = .;
* BSS_SECTION(0, 0)
* __bss_stop = .;
* _end = .;
*
* /DISCARD/ : {
* EXIT_TEXT
* EXIT_DATA
* *(.exitcall.exit)
* }
* STABS_DEBUG
* DWARF_DEBUG
* }
*
* [__init_begin, __init_end] is the init section that may be freed after init
* [_stext, _etext] is the text section
* [_sdata, _edata] is the data section
*
* Some of the included output section include their own set of constants.
* Examples are: [__initramfs_start, __initramfs_end] for initramfs and
* [__nosave_begin, __nosave_end] for the nosave data
*/
There is one majot issue in the minimal script I need to address.
All symbols are absolute (__init_begin, _stext etc) - I need to find a nice
way to make them non-absolute.
For now I and more interested in comments on the structure and the coverage
of the symbols.
I strikes me that [_stext, _etext] do not cover text in the init section.
And does [_sdata, _edata] cover RO_DATA?
What abut the order of the sections - are they significant for any archtecture?
I have used an order used by some of the embedded targets that allows
a maximum of code to reside inisde [__init_begin, __init_end].
Comments appreciated!
Sam
next reply other threads:[~2009-05-09 7:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-09 8:00 Sam Ravnborg [this message]
2009-05-09 23:27 ` Minimal linker script H. Peter Anvin
2009-05-09 23:27 ` H. Peter Anvin
2009-05-10 8:55 ` Sam Ravnborg
2009-05-10 17:53 ` H. Peter Anvin
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