Re: [PATCH] Report any problems with loading the VGA driver for PPC Macintosh targets

From: Programmingkid <programmingkidx@gmail.com>
To: BALATON Zoltan <balaton@eik.bme.hu>
Cc: Peter Maydell <peter.maydell@linaro.org>,
	QEMU Developers <qemu-devel@nongnu.org>,
	Greg Kurz <groug@kaod.org>, qemu-ppc <qemu-ppc@nongnu.org>,
	Howard Spoelstra <hsp.cat7@gmail.com>,
	David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [PATCH] Report any problems with loading the VGA driver for PPC Macintosh targets
Date: Tue, 31 Aug 2021 11:52:24 -0400	[thread overview]
Message-ID: <9E32E4A0-D1BB-4DDF-8F57-38BD5044DF1D@gmail.com> (raw)
In-Reply-To: <269a250-93ec-2e6-8813-5b65aa9fb76@eik.bme.hu>

> On Aug 30, 2021, at 5:47 PM, BALATON Zoltan <balaton@eik.bme.hu> wrote:
> 
> On Mon, 30 Aug 2021, Peter Maydell wrote:
>> On Mon, 30 Aug 2021 at 21:29, Programmingkid <programmingkidx@gmail.com> wrote:
>>> I found out that there are two pc-bios folders. One in the root directory
>>> and one in the build directory. QEMU is looking in the pc-bios folder
>>> located inside the build folder. The qemu_vga.ndrv file is only located
>>> in the root directory pc-bios folder. I think a good solution to this
>>> issue is to first remove one of the pc-bios folders. I'm not sure if it
>>> is just me who has two pc-bios folders or if everyone does.
>> 
>> Having two pc-bios folders is expected. The one in the source tree is
>> the one which has the files we actually carry around in git. The one
>> in the build tree is created by 'configure' and populated with symbolic
>> links back to the files in the source tree. We need this one because
>> the QEMU executable doesn't (and shouldn't) know where the source tree is:
>> when it is looking for files it will look in places relative to the
>> location of the executable itself (ie relative to the build tree)
>> as well as places set by configure (used when you install QEMU and
>> its various supporting files).
>> 
>> The reason qemu_vga.ndrv is not in the pc-bios folder in the build
>> tree is because when that file was added we forgot to add handling
>> for it in configure. I'm not sure why nobody else has fallen over
>> this in the intervening 3 years: running QEMU from the build tree
>> will never find the file, and it will not be installed via
>> 'make install' either.
> 
> This file is a driver for MacOS and not many people run that old OS. Those who do probably use Howard's binaries and follow his guides that tell you to use -L pc-bios on command line. I always wondered why that's needed when it should find it by default but this explains it and probably also your question why nobody complained.
> 
> Regards,
> BALATON Zoltan

This does sound like a good explanation. I am pretty sure I was able to use my Mac OS 9 VM without the -L option in the past and still have many video resolutions available. 