Re: [RFC PATCH (take #2)] i386: kill CONFIG_REGPARM completely

[Helge Hafting]

linux-os (Dick Johnson) wrote:

> On ix86 there are not enough registers to pass a significant parameter
> list all in registers! Like when you are printk()ing a dotted-quad IP
> address, etc. Registers ESI, EDI, and EBX are precious, that leaves
> EAX, ECX, EDX and possibly EBP for only 4 parameters. You need 5
> for the dotted quad IP address. If the compiler were to use the
> precious registers, the contents need to be saved on the stack.
> That negates any advantage to passing parameters in registers.
>  
I had the impression that REGPARM in i386 only passed the
first three arguments in registers, putting any further
paramters on the stack? 

Ought to help for all those 3-argument or less functions.

Helge Hafting
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/