[coreboot] __attribute__((stdcall)) vs. __attribute__((regparm(0)))

Carl-Daniel Hailfinger c-d.hailfinger.devel.2006 at gmx.net
Thu Oct 16 15:12:44 CEST 2008

[taking in Segher as gcc expert]

On 16.10.2008 14:53, Myles Watson wrote:
> On Wed, Oct 15, 2008 at 5:44 PM, Carl-Daniel Hailfinger wrote:
>> On 16.10.2008 01:13, Peter Stuge wrote:
>>> ron minnich wrote:
>>>> Myles, try setting -mregparm=0 and see if life is better.
>>> Good find.
>> __attribute__((stdcall)) will do this for you.
> It doesn't work for me.  I tried it in various places, but it doesn't change
> the way the parameters are handled.
> void __attribute__ ((stdcall)) callbiosint(void)
> __attribute__ ((stdcall)) void callbiosint(void)
> void  callbiosint(void) __attribute__ ((stdcall))
> biosint: INT# 0x18
> biosint: eax 0x2e ebx 0x10000 ecx 0xfe4 edx 0xcf11c
> biosint: ebp 0xc0000000 esp 0xd0000 edi 0x1a esi 0x0
> biosint:  ip 0x1022   cs 0xf  flags 0x2067
> BIOSINT: Unsupport int #0x18

What about __attribute__((regparm(0))) ?

The gcc documentation is not clear on this, but a call made this way
should take all of its arguments from the stack.

Segher: How do regparm(0) and stdcall differ for i386?



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