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From: "H. Peter Anvin" <hpa@zytor.com>
To: "Kevin O'Connor" <kevin@koconnor.net>
Cc: kvm-devel@lists.sourceforge.net, Avi Kivity <avi@qumranet.com>
Subject: Re: [ANN] Bochs bios ported to gcc
Date: Mon, 07 Apr 2008 09:18:31 -0700	[thread overview]
Message-ID: <47FA4957.5010800@zytor.com> (raw)
In-Reply-To: <20080407130545.GA22933@ohio.lan>

Kevin O'Connor wrote:
> On Sun, Apr 06, 2008 at 11:42:11PM -0700, H. Peter Anvin wrote:
>> bcc is truly horrible.  gcc is, of course, best, although it does produce 
>> bloated 16-bit code.
> 
> With gcc, the text size has actually been significantly reduced - I'm
> not sure if this is because I'm using -fwhole-program and -Os or if it
> is just the result of bcc being so bad.
> 

The 16-bit code is still horrid.  I have done some experiments with a 
16-bit backend to gcc last summer, and even when it could barely crawl, 
and had effectively no optimizations, it still produced 15% smaller code 
than the 32-bit backend with .code16gcc and the best optimizations I 
could find.

> The biggest problem I've run into is stack usage on the 16-bit bios
> calls.
> 
>> For "proper" 16-bit code, OpenWatcom is currently the 
>> best open source compiler, and it's actually getting usable even on a Linux 
>> host.
> 
> One of the developers on the bochs list also recommended OpenWatcom.
> 
> The bios currently has quite a bit of 32bit code in addition to the
> 16bit code.  It's very convenient to be able to compile the same code
> in both modes (eg, printf, inb, etc.).  I'd need to move both 32bit
> and 16bit code to OpenWatcom to do this.

Yes, of course.  OpenWatcom does do both, although I think gcc is a 
better compiler than OpenWatcom in 32-bit mode.  OpenWatcom isn't bad, 
though.

As long as it's just C, it's not really an issue, though.

	-hpa

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      reply	other threads:[~2008-04-07 16:18 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-04-02  1:42 [ANN] Bochs bios ported to gcc Kevin O'Connor
2008-04-06 12:05 ` Avi Kivity
2008-04-06 15:03   ` Kevin O'Connor
2008-04-07  6:42   ` H. Peter Anvin
2008-04-07 13:05     ` Kevin O'Connor
2008-04-07 16:18       ` H. Peter Anvin [this message]

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