qemu-riscv: Add initrd support patch

pkgs/applications/virtualization/qemu/riscv-initrd.patch

@@ -0,0 +1,98 @@
+From 44b0f612499764dad425d467aadacb01fbd4a920 Mon Sep 17 00:00:00 2001
+From: Shea Levy <shea@shealevy.com>
+Date: Tue, 20 Feb 2018 07:59:43 -0500
+Subject: [PATCH] riscv: Respect the -initrd flag.
+
+Logic for initrd start address borrowed from arm/boot.c
+---
+ hw/riscv/virt.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++---
+ 1 file changed, 46 insertions(+), 3 deletions(-)
+
+diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
+index 46d95b2b79..5c7d191a3f 100644
+--- a/hw/riscv/virt.c
++++ b/hw/riscv/virt.c
+@@ -77,7 +77,35 @@ static uint64_t load_kernel(const char *kernel_filename)
+     return kernel_entry;
+ }
+ 
+-static void create_fdt(RISCVVirtState *s, const struct MemmapEntry *memmap,
++static hwaddr load_initrd(const char *filename, uint64_t mem_size,
++                          uint64_t kernel_entry, hwaddr *start)
++{
++    int size;
++
++    /* We want to put the initrd far enough into RAM that when the
++     * kernel is uncompressed it will not clobber the initrd. However
++     * on boards without much RAM we must ensure that we still leave
++     * enough room for a decent sized initrd, and on boards with large
++     * amounts of RAM we must avoid the initrd being so far up in RAM
++     * that it is outside lowmem and inaccessible to the kernel.
++     * So for boards with less  than 256MB of RAM we put the initrd
++     * 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 * 1024 * 1024);
++
++    size = load_ramdisk(filename, *start, mem_size - *start);
++    if (size == -1) {
++        size = load_image_targphys(filename, *start, mem_size - *start);
++        if (size == -1) {
++          error_report("qemu: could not load ramdisk '%s'", filename);
++          exit(1);
++        }
++    }
++    return *start + size;
++}
++
++static void *create_fdt(RISCVVirtState *s, const struct MemmapEntry *memmap,
+     uint64_t mem_size, const char *cmdline)
+ {
+     void *fdt;
+@@ -233,6 +261,8 @@ static void create_fdt(RISCVVirtState *s, const struct MemmapEntry *memmap,
+     qemu_fdt_setprop_string(fdt, "/chosen", "stdout-path", nodename);
+     qemu_fdt_setprop_string(fdt, "/chosen", "bootargs", cmdline);
+     g_free(nodename);
++
++    return fdt;
+ }
+ 
+ static void riscv_virt_board_init(MachineState *machine)
+@@ -246,6 +276,7 @@ static void riscv_virt_board_init(MachineState *machine)
+     char *plic_hart_config;
+     size_t plic_hart_config_len;
+     int i;
++    void *fdt;
+ 
+     /* Initialize SOC */
+     object_initialize(&s->soc, sizeof(s->soc), TYPE_RISCV_HART_ARRAY);
+@@ -265,7 +296,8 @@ static void riscv_virt_board_init(MachineState *machine)
+         main_mem);
+ 
+     /* create device tree */
+-    create_fdt(s, memmap, machine->ram_size, machine->kernel_cmdline);
++    fdt = create_fdt(s, memmap, machine->ram_size,
++                     machine->kernel_cmdline);
+ 
+     /* boot rom */
+     memory_region_init_ram(boot_rom, NULL, "riscv_virt_board.bootrom",
+@@ -273,7 +305,18 @@ static void riscv_virt_board_init(MachineState *machine)
+     memory_region_add_subregion(system_memory, 0x0, boot_rom);
+ 
+     if (machine->kernel_filename) {
+-        load_kernel(machine->kernel_filename);
++        uint64_t kernel_entry = load_kernel(machine->kernel_filename);
++
++        if (machine->initrd_filename) {
++            hwaddr start;
++            hwaddr end = load_initrd(machine->initrd_filename,
++                                     machine->ram_size, kernel_entry,
++                                     &start);
++            qemu_fdt_setprop_cell(fdt, "/chosen",
++                                  "linux,initrd-start", start);
++            qemu_fdt_setprop_cell(fdt, "/chosen", "linux,initrd-end",
++                                  end);
++        }
+     }
+ 
+     /* reset vector */

pkgs/applications/virtualization/qemu/riscv.nix

@@ -15,6 +15,8 @@
 in lib.overrideDerivation qemu (orig: {
   name = "${(builtins.parseDrvName qemu.name).name}-${version}pre${revCount}_${shortRev}";
   inherit src;
+  # https://github.com/riscv/riscv-qemu/pull/109
+  patches = orig.patches ++ [ ./riscv-initrd.patch ];
   configureFlags = orig.configureFlags ++ [ "--target-list=${lib.concatStringsSep "," targets}" ];
   postInstall = null;
 })