Public bug reported: I attempted to run qemu with a ram disk. However, when reading the contents of the disk from within the VM I only get back zeros.
I was able to trace the issue to a mismatch of expectations on line 93 of hw/riscv/virt.c. Specifically, when running in 32-bit mode the value of kernel_entry is sign extended to 64-bits, but load_image_targphys expects the start address to not be sign extended. Straw man patch (works for 32-bit but would probably break 64-bit VMs?): diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c index e7f0716fb6..32216f993c 100644 --- a/hw/riscv/virt.c +++ b/hw/riscv/virt.c @@ -90,7 +90,7 @@ static hwaddr load_initrd(const char *filename, uint64_t mem_size, * halfway into RAM, and for boards with 256MB of RAM or more we put * the initrd at 128MB. */ - *start = kernel_entry + MIN(mem_size / 2, 128 * MiB); + *start = (kernel_entry & 0xffffffff) + MIN(mem_size / 2, 128 * MiB); size = load_ramdisk(filename, *start, mem_size - *start); if (size == -1) { Run command: $ qemu/build/riscv32-softmmu/qemu-system-riscv32 -machine virt -kernel mykernel.elf -nographic -initrd payload Commit hash: 3a183e330dbd7dbcac3841737ac874979552cca2 ** Affects: qemu Importance: Undecided Status: New -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1814343 Title: Initrd not loaded on riscv32 Status in QEMU: New Bug description: I attempted to run qemu with a ram disk. However, when reading the contents of the disk from within the VM I only get back zeros. I was able to trace the issue to a mismatch of expectations on line 93 of hw/riscv/virt.c. Specifically, when running in 32-bit mode the value of kernel_entry is sign extended to 64-bits, but load_image_targphys expects the start address to not be sign extended. Straw man patch (works for 32-bit but would probably break 64-bit VMs?): diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c index e7f0716fb6..32216f993c 100644 --- a/hw/riscv/virt.c +++ b/hw/riscv/virt.c @@ -90,7 +90,7 @@ static hwaddr load_initrd(const char *filename, uint64_t mem_size, * halfway into RAM, and for boards with 256MB of RAM or more we put * the initrd at 128MB. */ - *start = kernel_entry + MIN(mem_size / 2, 128 * MiB); + *start = (kernel_entry & 0xffffffff) + MIN(mem_size / 2, 128 * MiB); size = load_ramdisk(filename, *start, mem_size - *start); if (size == -1) { Run command: $ qemu/build/riscv32-softmmu/qemu-system-riscv32 -machine virt -kernel mykernel.elf -nographic -initrd payload Commit hash: 3a183e330dbd7dbcac3841737ac874979552cca2 To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1814343/+subscriptions