From 43f8cfdd8372146b37a6a63ea5f3d7b1e6befa6c Mon Sep 17 00:00:00 2001
From: Thomas Oltmann <thomas.oltmann.hhg@gmail.com>
Date: Sat, 20 Dec 2025 17:12:36 +0100
Subject: [PATCH] Got OVMF on bochs running, kinda

---
 bochsrc      | 77 +++++++++++++++++++++++++++-------------------------
 src/vintel.c |  6 ++++
 2 files changed, 46 insertions(+), 37 deletions(-)

diff --git a/bochsrc b/bochsrc
index d9f6fc9..9dce6ef 100644
--- a/bochsrc
+++ b/bochsrc
@@ -1,37 +1,40 @@
-# configuration file generated by Bochs
-plugin_ctrl: unmapped=1, biosdev=1, speaker=1, extfpuirq=1, parallel=1, serial=1
-memory: host=64, guest=64
-romimage: file="/usr/share/OVMF/x64/MICROVM.fd", address=0x0, options=none
-vgaromimage: file="/usr/share/bochs/VGABIOS-lgpl-latest-cirrus"
-boot: floppy
-floppy_bootsig_check: disabled=0
-# no floppya
-# no floppyb
-ata0: enabled=1, ioaddr1=0x1f0, ioaddr2=0x3f0, irq=14
-ata0-master: type=none
-ata0-slave: type=none
-ata1: enabled=1, ioaddr1=0x170, ioaddr2=0x370, irq=15
-ata1-master: type=none
-ata1-slave: type=none
-pci: enabled=1, chipset=i440fx, slot1=cirrus
-vga: extension=cirrus, update_freq=5, realtime=1
-cpu: count=1, ips=4000000, model=bx_generic, reset_on_triple_fault=1, cpuid_limit_winnt=0, ignore_bad_msrs=1, mwait_is_nop=0
-cpuid: level=6, stepping=3, model=3, family=6, vendor_string="GenuineIntel", brand_string="              Intel(R) Pentium(R) 4 CPU        "
-cpuid: mmx=1, apic=xapic, simd=sse2, sse4a=0, misaligned_sse=0, sep=1, movbe=0, adx=0
-cpuid: aes=0, sha=0, xsave=0, xsaveopt=0, x86_64=1, 1g_pages=0, pcid=0, fsgsbase=0
-#cpuid: smep=0, smap=0, mwait=1, vmx=1
-print_timestamps: enabled=0
-port_e9_hack: enabled=0
-private_colormap: enabled=0
-clock: sync=none, time0=local, rtc_sync=0
-# no cmosimage
-# no loader
-log: -
-logprefix: %t%e%d
-debug: action=ignore
-info: action=report
-error: action=report
-panic: action=ask
-keyboard: type=mf, serial_delay=250, paste_delay=100000, user_shortcut=none
-mouse: type=ps2, enabled=0, toggle=ctrl+mbutton
-com1: enabled=1, mode=null
+cpu: model=corei5_lynnfield_750, count=1, reset_on_triple_fault=1
+#cpuid: x86_64=1, mmx=1, sep=1, simd=sse4_2, apic=xapic, aes=1, movbe=1, xsave=1
+#cpuid: family=6, model=0x1a, stepping=5
+
+memory: guest=1024, host=1024
+
+#romimage: file=$BXSHARE/BIOS-bochs-latest, options=fastboot
+#romimage: file=DEBUGX64_OVMF.fd, address=0x0, options=none
+#romimage: file=OVMF-pure-efi.fd, address=0x0, options=none
+romimage: file=/usr/share/OVMF/x64/OVMF.fd, address=0x0, options=none
+
+#vgaromimage: file=$BXSHARE/VGABIOS-lgpl-latest-cirrus.bin
+vgaromimage: file=$BXSHARE/VGABIOS-lgpl-latest.bin
+vga: extension=cirrus
+
+mouse: enabled=0
+
+pci: enabled=1, chipset=i440fx, slot1=cirrus
+
+ata0: enabled=1, ioaddr1=0x1f0, ioaddr2=0x3f0, irq=14
+ata1: enabled=1, ioaddr1=0x170, ioaddr2=0x370, irq=15
+ata2: enabled=0, ioaddr1=0x1e8, ioaddr2=0x3e0, irq=11
+ata3: enabled=0, ioaddr1=0x168, ioaddr2=0x360, irq=9
+
+ata0-master: type=disk, mode=flat, path="disk.img", cylinders=1024, heads=1, spt=16
+boot: disk
+
+#ata0-master: type=cdrom, path=UefiShell.iso, status=inserted, model="UefiShell.iso"
+#boot: cdrom
+
+panic: action=ask
+error: action=report
+info: action=report
+#debug: action=ignore, apic0=report, pic=report, ioapic=report
+debug: action=ignore, keyboard=report
+
+#com1: enabled=1, mode=socket-server, dev=localhost:1111
+port_e9_hack: enabled=1
+
+log: log.txt
diff --git a/src/vintel.c b/src/vintel.c
index 30127aa..5f46a29 100644
--- a/src/vintel.c
+++ b/src/vintel.c
@@ -39,6 +39,12 @@ vintel_has_support(char *err, size_t errmax)
 		return false;
 	}
 
+    /* Bochs does not enable VMX, relying on the BIOS instead.
+     * OVMF, the UEFI BIOS, only enables VMX if told so through a fw_cfg device,
+     * which is not emulated by Bochs. As a workaround, we try to enable VMX
+     * ourselves ... */
+    writemsr64(IA32_FEATURE_CONTROL, readmsr64(IA32_FEATURE_CONTROL) | 0x5);
+
 	if (!vintel_has_bios_support()) {
 		strlcpy(err, "VT-x support is not enabled in BIOS.", errmax);
 		return false;