On 8/7/2023 3:50 PM, Wu, Fei wrote:

Hi All,

I am working on enabling PCIe passthrough on qemu risc-v, in order for the guest to access the host x86 pci resource directly, ram on guest won't cover this range, so if guest has 4GB ram, two ranges are created:

1. 2G-3G
2. 4G-7G

u-boot is not able to handle this but reports:

Reserving 869k for U-Boot at: ff725000 initcall: 0000000080216f94 Reserving 8320k for malloc() at: fef05000 initcall: 0000000080216ee8 Unhandled exception: Store/AMO access fault

EP: 0000000080201a38 RA: 0000000080216f10 TVAL: 00000000fef04f90

It looks like fdtdec_setup_mem_size_base() in u-boot sets ram_base/size without considering all memory nodes, and board_get_usable_ram_top() returns 4G-1 that causes gd->relocaddr set to the wrong address which has no ram backed. More details can be found here: https://patchew.org/QEMU/20230731015317.1026996-1-fei2.wu@intel.com/

Can we add support for this multi-range ram setting? Any comments?

The test command is: qemu-system-riscv64 -machine virt -nographic -m 4G -smp 4 \ -bios /usr/lib/riscv64-linux-gnu/opensbi/generic/fw_jump.elf \ -kernel /home/wufei/nvme/u-boot/u-boot.bin \ -device vfio-pci,host=01:00.0 -device vfio-pci,host=01:00.1 \ -drive file=ubuntu-22.04.1-preinstalled-server-riscv64+unmatched.img,if=virtio,format=raw

Here is a quick fix, is it good?

diff --git a/arch/riscv/cpu/generic/dram.c b/arch/riscv/cpu/generic/dram.c index 44e11bd56c..fb53a57b4e 100644 --- a/arch/riscv/cpu/generic/dram.c +++ b/arch/riscv/cpu/generic/dram.c @@ -13,7 +13,7 @@ DECLARE_GLOBAL_DATA_PTR;

int dram_init(void) { - return fdtdec_setup_mem_size_base(); + return fdtdec_setup_mem_size_base_lowest(); }

int dram_init_banksize(void) diff --git a/configs/qemu-riscv64_smode_defconfig b/configs/qemu-riscv64_smode_defconfig index 1d0f021ade..de08a49dab 100644 --- a/configs/qemu-riscv64_smode_defconfig +++ b/configs/qemu-riscv64_smode_defconfig @@ -1,6 +1,6 @@ CONFIG_RISCV=y CONFIG_SYS_MALLOC_LEN=0x800000 -CONFIG_NR_DRAM_BANKS=1 +CONFIG_NR_DRAM_BANKS=2 CONFIG_HAS_CUSTOM_SYS_INIT_SP_ADDR=y CONFIG_CUSTOM_SYS_INIT_SP_ADDR=0x80200000 CONFIG_ENV_SIZE=0x20000

Thanks, Fei.