Re: System Call parameters

[H. Peter Anvin]

Followup to:  <Pine.LNX.4.53.0304161256130.11667@chaos>
By author:    "Richard B. Johnson" <[e-mail]>
In newsgroup: linux.dev.kernel
>
> How does the kernel get more than five parameters?
> 
> Currently...
> 	eax	= function code
> 	ebx	= first parameter
> 	ecx	= second parameter
> 	edx	= third parameter
> 	esi	= fourth parameter
> 	edi	= fifth parameter
> 
> Some functions like mmap() take 6 parameters!
> Does anybody know how these parameters get passed?
> I have an "ultra-light" 'C' runtime library I have
> been working on and, so-far, I've got everything up
> to mmap()  (in syscall.h) (89 functions) working.
> I thought, maybe ebp was being used, but it doesn't
> seem to be the case.
> 

%ebp is used.

However, on i386, SYS_mmap is a four-parameter system call where the
last parameter is a pointer to a parameter block.  SYS_mmap2 is the
full six-parameter sane version.

You may want to check out klibc.

	-hpa

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