On Tue, Feb 7, 2017 at 10:51 AM, J. Tang tang@jtang.org wrote:
On 2017-02-06, at 01:35, Bin Meng bmeng.cn@gmail.com wrote:
+Simon,
I do not have a GCC5 toolchain to test this. I suspect this is only exposed with GCC5, or GCC 5.4? Is there any parameter to control the behavior?
I observed a similar behavior with GCC 5.3.
As an experiment, I disabled CONFIG_CC_OPTIMIZE_FOR_SIZE. This did not change the sizes; the handler for IRQs 0 through 19 were still 4 bytes while the rest were 7 bytes.
Although I am not an expert x86 assembly writer, I was able to force the assembler to generate 32-bit jumps with the following:
diff --git a/arch/x86/cpu/interrupts.c b/arch/x86/cpu/interrupts.c index 5f6cdd3..9917d09 100644 --- a/arch/x86/cpu/interrupts.c +++ b/arch/x86/cpu/interrupts.c @@ -32,7 +32,7 @@ DECLARE_GLOBAL_DATA_PTR; ".type irq_"#x", @function\n" \ "irq_"#x":\n" \ "pushl $"#x"\n" \
"jmp irq_common_entry\n"
"jmp.d32 irq_common_entry\n"static char *exceptions[] = { "Divide Error",
This worked for both GCC 5.4 and 4.9.
Looks good. Can you prepare a patch?
Regards, Bin