Fitting Four 32 GB Resizable BARs Behind a PCIe Switch on Linux
Summary
The post documents the challenge of fitting four 32 GB Resizable BARs behind a PCIe switch on Linux using a Broadcom PEX88096 and multiple GPUs. It explains BIOS/address space constraints, a Linux 7.0 bridge window sizing bug, and a workaround using an out-of-tree kernel module to pad BARs and enable full 32 GB windows, with references to patches and sources.