> For the complete documentation index, see [llms.txt](https://docs.vergeos-demo.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.vergeos-demo.com/knowledge-base/virtual-machines/vm-advanced-options.md). # VM Advanced Options ## Overview The VM Advanced Options field allows power users to fine-tune virtual machine parameters beyond what's available in the standard UI. These options provide granular control over CPU features, hardware emulation, and device behavior. {% hint style="warning" %} **Use with Caution** Advanced options can significantly impact VM performance and stability. Only modify these settings if you understand their implications. Incorrect values may prevent your VM from starting. {% endhint %} ## Format Advanced options use a simple key-value format, with one option per line: ``` option1=value1 option2=value2 option3=value3 ``` ## Available Options ### CPU and Memory #### CPU Threads ``` cpu.threads=2 ``` Sets the number of CPU threads per core. Default is 1. **Use case:** Enabling SMT (Simultaneous Multi-Threading) for applications that benefit from hyperthreading. #### Memory Pre-allocation ``` mem-prealloc=1 ``` Pre-allocates all VM memory at startup instead of allocating on demand. **Use case:** Reduces memory allocation latency for performance-critical workloads. Useful for real-time applications or when using hugepages. ### UUID Configuration You can customize the VM's UUID (Universally Unique Identifier) to match specific requirements, such as software licensing or migration scenarios. #### System UUID ``` smbios.type1.uuid=550e8400-e29b-41d4-a716-446655440000 ``` Sets the system UUID presented to the guest OS. This is the primary UUID that most software checks. **Use cases:** * Migrating VMs from other platforms while preserving licensing * Software that validates against a specific UUID * Cloning VMs that need unique identifiers {% hint style="warning" %} **UUID Format** UUIDs must be in standard format: `xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx` (8-4-4-4-12 hexadecimal characters). Invalid formats will prevent the VM from starting. {% endhint %} {% hint style="success" %} **Generating UUIDs** On Linux: `uuidgen` On Windows PowerShell: `[guid]::NewGuid()` Online: Use any UUID generator tool {% endhint %} ### SMBIOS Customization SMBIOS (System Management BIOS) options allow you to customize the hardware information presented to the guest OS. #### Type 0 - BIOS Information ``` smbios.type0.vendor=American Megatrends Inc. smbios.type0.version=2.0 smbios.type0.date=01/01/2023 ``` #### Type 1 - System Information ``` smbios.type1.product=Custom Server smbios.type1.version=1.0 smbios.type1.sku=SKU123 smbios.type1.family=Server Family ``` #### Type 2 - Baseboard Information ``` smbios.type2.manufacturer=Custom Manufacturer smbios.type2.product=Custom Board smbios.type2.version=1.0 ``` #### Type 3 - Enclosure Information ``` smbios.type3.manufacturer=Custom Chassis smbios.type3.version=1.0 smbios.type3.sku=CHASSIS123 ``` #### Type 4 - Processor Information ``` smbios.type4.version=Intel(R) Xeon(R) CPU E5-2680 v4 smbios.type4.manufacturer=Intel ``` **Use cases for SMBIOS:** * Software licensing that checks hardware signatures * Applications expecting specific hardware configurations * Testing scenarios requiring specific system identification ### Network Interface Tuning For each NIC, you can tune queue parameters using the NIC's asset ID: ``` nic1.txqueuelen=2000 nic1.numtxqueues=4 nic1.numrxqueues=4 ``` **Use cases:** * High-throughput network applications * Reducing network latency * Optimizing for specific network workloads ### Machine-Specific Parameters Customize QEMU machine parameters: ``` machine.cap-cfpc=broken machine.cap-sbbc=broken machine.cap-ibs=broken ``` **Use cases:** * Working around CPU security mitigation issues * Compatibility with specific guest operating systems * Performance optimization for trusted environments ### RTC (Real-Time Clock) Options ``` rtc.drift-fix=slew ``` **Use cases:** * Fixing time drift issues in VMs * Synchronization requirements for time-sensitive applications ## Device-Specific Options You can set parameters for any device using its asset ID: ``` device1.guest-reset=true device1.guest-resets-all=false ``` For drives: ``` drive1.cache=writeback drive1.detect-zeroes=on ``` ## Common Use Cases ### High-Performance Computing ``` cpu.threads=2 mem-prealloc=1 nic1.numtxqueues=8 nic1.numrxqueues=8 ``` ### Windows Licensing Compliance ``` smbios.type1.manufacturer=Dell Inc. smbios.type1.product=PowerEdge R740 smbios.type1.serial=ABC123 ``` ### Preserving UUID After Migration ``` smbios.type1.uuid=550e8400-e29b-41d4-a716-446655440000 ``` Use when migrating a VM from another platform and the guest OS has software tied to the original UUID. ### Network Optimization ``` nic1.txqueuelen=5000 nic1.numtxqueues=4 nic1.numrxqueues=4 ``` ## Best Practices {% hint style="success" %} **Testing Recommendations** 1. Test advanced options in a non-production environment first 2. Document any advanced options you use for future reference 3. Only add options that solve specific problems or requirements 4. Monitor VM performance after applying advanced options {% endhint %} ## Troubleshooting If your VM fails to start after adding advanced options: 1. Remove all advanced options and try starting the VM 2. Add options back one at a time to identify the problematic setting 3. Check the VM logs for specific error messages 4. Verify the syntax - ensure each option is on its own line with no extra spaces {% hint style="info" %} **Version Compatibility** Some advanced options may not be available on all VergeOS versions. Options are processed dynamically, so unsupported options are typically ignored rather than causing errors. {% endhint %} {% hint style="info" %} **Document Information** * Last Updated: 2026-01-24 * VergeOS Version: 26.1 {% endhint %} --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.vergeos-demo.com/knowledge-base/virtual-machines/vm-advanced-options.md?ask= ``` The question should be specific, self-contained, and written in natural language. 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