x86: Document linker script ASSERT() quirk

Older binutils breaks if ASSERT() is used without a sink
for the output.

For example 2.14.90.0.6 is known to be broken, the link
fails with:

  LD      .tmp_vmlinux1
  ld:arch/x86/kernel/vmlinux.lds:678: parse error

Document this quirk in all three files that use it.

  See:    http://marc.info/?l=linux-kbuild&m=124930110427870&w=2
  See[2]: d2ba8b2 ("x86: Fix assert syntax in vmlinux.lds.S")

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Roland McGrath <roland@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
LKML-Reference: <4AD6523D.5030909@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2009-10-16 07:18:46 +02:00
parent 012abeea66
commit a5912f6b3e
3 changed files with 9 additions and 0 deletions

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@ -53,6 +53,9 @@ SECTIONS
/DISCARD/ : { *(.note*) }
/*
* The ASSERT() sink to . is intentional, for binutils 2.14 compatibility:
*/
. = ASSERT(_end <= 0x8000, "Setup too big!");
. = ASSERT(hdr == 0x1f1, "The setup header has the wrong offset!");
/* Necessary for the very-old-loader check to work... */

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@ -57,5 +57,8 @@ SECTIONS
*(.note*)
}
/*
* The ASSERT() sink to . is intentional, for binutils 2.14 compatibility:
*/
. = ASSERT(_end <= WAKEUP_SIZE, "Wakeup too big!");
}

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@ -305,6 +305,9 @@ SECTIONS
#ifdef CONFIG_X86_32
/*
* The ASSERT() sink to . is intentional, for binutils 2.14 compatibility:
*/
. = ASSERT((_end - LOAD_OFFSET <= KERNEL_IMAGE_SIZE),
"kernel image bigger than KERNEL_IMAGE_SIZE");
#else