Home

Settings Research Documentation

This is largely documentation of the --pcfrom option and why decisions were made they way that they were.

HVF/KVM Accelleration

HVF/KVM Accelleration causes problem with older code. Since the "turn-around" for safe usage is 2000, qcl won't enable KVM acceleration by default until --pcfrom 2001 is used. The options --nohvf, --nokvm, --usehvf, and --usekvm can be used to override decisions made by qcl. (HVF and KVM are synonymous to qcl -- it will use the appropriate accelerator for the platform it's running on.)

Operating System	RTR	KVM Problems
Windows 95	1995	Assumed from Windows 98
Red Hat Linux 5.0	1997	Hangs the cirrus driver
Windows 98	1998	Crashes NDIS (networking)
Turbo Linux 6.0	2000	Hangs the cirrus driver. Hangs LILO.
Windows 2000	2000	No problems
Mandrake Linux 8.1	2001	No problems
Fedora Core 1	2003	No problems
SuSE Linux 9.3	2003	No problems

CPU selection

CPU parameters are pretty much an exact reflection of what was available at the time. Operating systems give a large leeway to the processors they run on.

QEMU does not provide a pentium4 option. This is probably due to the then-exclusive (i786/pentium4) instruction set not seeing much use in the 32-bit space, with everyone sticking with the Pentium III (i686) instead. The Pentium 4 was released in 2000, and Hyper Threading was introduced in 2004. But with no pentium4 target in QEMU, there is a bit of a gap.

(The i786/pentium4 instruction set sees full use in all 64-bit CPUs as they are part of the x86_64_v1 spec.)

While AMD released the AMD Athlon 64 in 2003, there is no ahtlon64 target. There is an athlon target, but it's the original 32-bit one from 1999. The next-best thing from QEMU is Opteron_G1.

As far as the athlon target is concerned, that's passed on in favor of Pentium III since AMD has announced that it even they will be dropping 3DNow! instructions from their future processors.

Year	CPU	Cores
1993	pentium	1
1997	pentium2	1
1999	pentium3	1
2004	Opteron_G1	1
2006	Conroe	2
2007	Penryn	4
2008	Nahalem	8
2010	Westmere	12
2011	SandyBridge	12
2013	Haswell	12

VirtIO was introduced in 2013, so hardware targeting stops here in favor of using VirtIO.

GPU Selection

While choosing a CPU can be done largely independent of the operating system in use, graphics selection relies more on what drivers operating sytems bundled at the time.

Operating System	RTR	cirrus-vga	ati-vga model=rage128p	ati-vga model=rv100	VGA
Windows 95	1995	🆗	🕙	🕙
Red Hat 5.0	1997	💩	🕙	🕙	❌
Windows 98	1998	🆗	🕙	🕙
Turbo Linux 6.0	2000	💩	❌	🕙
Windows 2000 Pro	2000	🆗	❌	🕙
Windows XP	2001	🆗	❌	❌
Mandrake 8.1	2001	🆗	❌	❌
Arch Linux 0.1	2002				🆗
Fedora Core 1	2003		💩	💩	🆗
SuSE 9.3 Pro	2005		🆗	🆗	🆗

❌ = No drivers / does not work at all • 🕙 = OS pre-dates GPU • 💩 = Card supported but emulation flawed • 🆗 = Fully works.

Networking

Networking also relies on OS support. While Windows support for NE2000 is good, Linux support for the card is bleh. Good NIC support between the two starts with the AMD PCnet card. The Realtek 8139 also has good support on both Linux and Windows.

qcl uses ne2k_pci up to --pcfrom 1996 and uses pcnet for --pcfrom 1997 and --pcfrom 1998

qcl implements rtl8139 starting with --pcfrom 2000

These choices can be overridden with the --ne2k, --pcnet, and --realtek options.

Operating System	RTR	ne2k_pci 1988	pcnet 1996	rtl8139 1999	e1000e 2013
Windows 95	1995	🆗	🕙	🕙	🕙
Red Hat 5.0	1997	❌	🆗	🕙	🕙
Windows 98	1998	🆗	🆗	🕙	🕙
Turbo Linux 6.0	2000	❌	🆗	🆗	🕙
Windows 2000 Pro	2000	🆗	🆗	🆗	🕙
Windows XP	2001	🆗	🆗	🆗	🕙
Mandrake 8.1	2001		🆗	🆗	🕙
Arch Linux 0.1	2002				🕙
Fedora Core 1	2003		🆗	🆗	🕙
SuSE 9.3 Pro	2005		🆗	🆗	🕙