GoKawiilDeveloper builds gpu-rebar-layout tool to enable 32 GB Resizable BAR on multi-GPU Linux rig
A hobbyist detailed how they got peer-to-peer memory access working across four AMD Radeon AI PRO R9700 cards and two RTX 3090s connected through a Broadcom PEX88096 PCIe switch on Linux. They released a kernel module called gpu-rebar-layout on GitHub that manually resizes each card's BAR to 32 GB after boot, working around a BIOS limitation and a Linux kernel bug that prevents the system from allocating enough address space for six large BARs at once.