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Message-ID: <20151108052358.GN3818@brightrain.aerifal.cx>
Date: Sun, 8 Nov 2015 00:23:58 -0500
From: Rich Felker <dalias@...c.org>
To: musl@...ts.openwall.com
Subject: Re: sys/io.h lacks inb_p and outb_p on x86
On Sun, Nov 08, 2015 at 12:13:37PM +0700, Рысь wrote:
> On Sat, 7 Nov 2015 23:50:45 -0500
> Rich Felker <dalias@...c.org> wrote:
>
> > On Sun, Nov 08, 2015 at 11:26:55AM +0700, Рысь wrote:
> > > x86 arch lacks inb_p and outb_p inline functions. This is required
> > > for memtest86+.
> > >
> > > I don't know how properly make an assembly here, so when making
> > > memtest I copied sys/io.h into local directory, and copied these
> > > functions from uClibc.
> > >
> > > I attach modified header for reference (they should go into
> > > bits/io.h).
> >
> > Any idea what these are intended to do? Are they documented anywhere?
> >
> > Rich
>
> I can't say much, but looking into memtest code I see they're used only
> for beeping a PC speaker.
>
> Comment in io.h include file of memtest says:
>
> * This file contains the definitions for the x86 IO instructions
> * inb/inw/inl/outb/outw/outl and the "string versions" of the same
> * (insb/insw/insl/outsb/outsw/outsl). You can also use "pausing"
> * versions of the single-IO instructions (inb_p/inw_p/..).
>
> However memtest builds with assumption they're present in sys/io.h from
> host and io.h included with memtest does not define inb_p/outb_p in any
> way.
>
> I probably will go with uClibc defines, or just nop memtest beeper.
See http://stackoverflow.com/questions/6793899/what-does-the-0x80-port-address-connects
So apparently these are convenience functions to show the most recent
port io that was performed on a hardware debugging device in case the
memtest crashes. I don't mind adding them is software expects them to
be there, but they should be written in terms of the existing
functions rather than duplicating asm.
Rich
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