I’m using my Chromebook as a KVM host machine with an Intel i5-10310U CPU, which supports GPU sharing with VMs(Intel gvt-g). However, the default GPU RAM allocation of 256MB in coreboot is too small to create additional VMs. If I increase the GPU RAM to 1000MB, I can create more VMs that share the host GPU. I found some relevant keywords in the coreboot source code, but I’m not sure how to modify the settings. Can anyone help with the steps to increase the GPU RAM allocation in coreboot?
Haswell is 4th gen, cyan is a braswell device. None of that is applicable to your device.
IgdDvmt50PreAlloc is the correct FSP parameter, but you want the one in src/soc/intel/cannonlake/romstage/fsp_params.c. You cannot increase this above 128MB IIRC; the default is 64MB, not sure where you’re getting 256MB from.
In a few versions down the line, this will likely be configurable via the UEFI setup options.
Thanks! Are you the author of the Chromebook project? Your work is awesome!
I’ve been reviewing the file src/soc/intel/cannonlake/romstage/fsp_params.c and noticed the following:
/* Set IGD stolen size to 64MB. */
m_cfg->InternalGfx = 1;
m_cfg->IgdDvmt50PreAlloc = 2;
I’m not sure this is what I want to modify. According to the output from lspci, the prefetchable memory size is currently set to 256MB, and that’s the value I’d like to adjust.
00:02.0 VGA compatible controller: Intel Corporation CometLake-U GT2 [UHD Graphics] (rev 02) (prog-if 00 [VGA controller])
DeviceName: VGA compatible controller
Subsystem: Intel Corporation CometLake-U GT2 [UHD Graphics]
Flags: bus master, fast devsel, latency 0, IRQ 132, IOMMU group 0
Memory at b0000000 (64-bit, non-prefetchable) [size=16M]
Memory at a0000000 (64-bit, prefetchable) [size=256M]
I/O ports at 1000 [size=64]
Expansion ROM at 000c0000 [virtual] [disabled] [size=128K]
Capabilities:
Kernel driver in use: i915
Kernel modules: i915
Could you provide any guidance on how to modify the prefetchable memory size?
Thanks in advance!