On 04/06/2024 16.35, Paolo Bonzini wrote:
The bottom 32K of memory are generally reserved for use by the BIOS;
for example, traditionally the boot loader is placed at 0x7C00 and
the stack grows below that address.
It turns out that with some versions of clang, realmode.flat has
become big enough that it overlaps the stack used by the multiboot
option ROM loader. The result is that a couple instructions are
overwritten. Typically one or two tests fail and that's it...
Move the code above the forbidden region, in real 90s style.
Reported-by: Thomas Huth <thuth@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
x86/realmode.lds | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/x86/realmode.lds b/x86/realmode.lds
index 0ed3063b..e4782a98 100644
--- a/x86/realmode.lds
+++ b/x86/realmode.lds
@@ -1,6 +1,6 @@
SECTIONS
{
- . = 16K;
+ . = 32K;
stext = .;
.text : { *(.init) *(.text) }
. = ALIGN(4K);
This fails for me with:
ld -m elf_i386 -nostdlib -o x86/realmode.elf \
-T /home/thuth/devel/kvm-unit-tests/x86/realmode.lds x86/realmode.o
x86/realmode.o: in function `init_inregs':
/home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0x79): relocation
truncated to fit: R_386_16 against `.bss'
/home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0x82): relocation
truncated to fit: R_386_16 against `.bss'
/home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0x8b): relocation
truncated to fit: R_386_16 against `.bss'
/home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0x94): relocation
truncated to fit: R_386_16 against `.bss'
/home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0x9d): relocation
truncated to fit: R_386_16 against `.bss'
/home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0xa6): relocation
truncated to fit: R_386_16 against `.bss'
/home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0xaf): relocation
truncated to fit: R_386_16 against `.bss'
/home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0xb8): relocation
truncated to fit: R_386_16 against `.bss'
/home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0xc1): relocation
truncated to fit: R_386_16 against `.bss'
/home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0xca): relocation
truncated to fit: R_386_16 against `.bss'
/home/thuth/devel/kvm-unit-tests/x86/realmode.c:180:(.text+0xda): additional
relocation overflows omitted from the output
make: *** [/home/thuth/devel/kvm-unit-tests/x86/Makefile.common:107:
x86/realmode.elf] Error 1
Thomas
