Re: [Qemu-devel] [PATCH 2/5] PPC: Make MPC8544DS emulation work w/o KVM

["Edgar E. Iglesias" <edgar.iglesias@gmail.com>]

On Mon, May 02, 2011 at 01:04:04PM +0200, Alexander Graf wrote:
> The MPC8544DS board emulation was only used with KVM so far, so some
> parts of the code didn't provide proper values for non-KVM execution.
> 
> This patch makes the machine work without KVM enabled. To actually use
> this, you also need proper e500v2 MMU emulation.


Just a few inline questions...


> 
> Signed-off-by: Alexander Graf <agraf@suse.de>
> ---
>  hw/ppce500_mpc8544ds.c |   56 +++++++++++++++++++++++++++++++++++++++--------
>  1 files changed, 46 insertions(+), 10 deletions(-)
> 
> diff --git a/hw/ppce500_mpc8544ds.c b/hw/ppce500_mpc8544ds.c
> index 1b8a1c4..b5dd937 100644
> --- a/hw/ppce500_mpc8544ds.c
> +++ b/hw/ppce500_mpc8544ds.c
> @@ -28,6 +28,7 @@
>  #include "kvm_ppc.h"
>  #include "device_tree.h"
>  #include "openpic.h"
> +#include "ppc.h"
>  #include "ppce500.h"
>  #include "loader.h"
>  #include "elf.h"
> @@ -82,7 +83,7 @@ static int mpc8544_load_device_tree(target_phys_addr_t addr,
>  {
>      int ret = -1;
>  #ifdef CONFIG_FDT
> -    uint32_t mem_reg_property[] = {0, ramsize};
> +    uint32_t mem_reg_property[] = {0, cpu_to_be32(ramsize)};
>      char *filename;
>      int fdt_size;
>      void *fdt;
> @@ -103,15 +104,19 @@ static int mpc8544_load_device_tree(target_phys_addr_t addr,
>      if (ret < 0)
>          fprintf(stderr, "couldn't set /memory/reg\n");
>  
> -    ret = qemu_devtree_setprop_cell(fdt, "/chosen", "linux,initrd-start",
> -                                    initrd_base);
> -    if (ret < 0)
> -        fprintf(stderr, "couldn't set /chosen/linux,initrd-start\n");
> +    if (initrd_size) {
> +        ret = qemu_devtree_setprop_cell(fdt, "/chosen", "linux,initrd-start",
> +                                        initrd_base);
> +        if (ret < 0) {
> +            fprintf(stderr, "couldn't set /chosen/linux,initrd-start\n");
> +        }
>  
> -    ret = qemu_devtree_setprop_cell(fdt, "/chosen", "linux,initrd-end",
> -                                    (initrd_base + initrd_size));
> -    if (ret < 0)
> -        fprintf(stderr, "couldn't set /chosen/linux,initrd-end\n");
> +        ret = qemu_devtree_setprop_cell(fdt, "/chosen", "linux,initrd-end",
> +                                        (initrd_base + initrd_size));
> +        if (ret < 0) {
> +            fprintf(stderr, "couldn't set /chosen/linux,initrd-end\n");
> +        }
> +    }
>  
>      ret = qemu_devtree_setprop_string(fdt, "/chosen", "bootargs",
>                                        kernel_cmdline);
> @@ -145,6 +150,13 @@ static int mpc8544_load_device_tree(target_phys_addr_t addr,
>  
>          mpc8544_copy_soc_cell(fdt, buf, "clock-frequency");
>          mpc8544_copy_soc_cell(fdt, buf, "timebase-frequency");
> +    } else {
> +        const uint32_t freq = 400000000;
> +
> +        qemu_devtree_setprop_cell(fdt, "/cpus/PowerPC,8544@0",
> +                                  "clock-frequency", freq);
> +        qemu_devtree_setprop_cell(fdt, "/cpus/PowerPC,8544@0",
> +                                  "timebase-frequency", freq);
>      }
>  
>      ret = rom_add_blob_fixed(BINARY_DEVICE_TREE_FILE, fdt, fdt_size, addr);
> @@ -156,6 +168,21 @@ out:
>      return ret;
>  }
>  
> +/* Create reset TLB entries for BookE, spanning the 32bit addr space.  */
> +static void mmubooke_create_initial_mapping(CPUState *env,
> +                                     target_ulong va,
> +                                     target_phys_addr_t pa)
> +{
> +    ppcemb_tlb_t *tlb = &env->tlb[512].tlbe;
> +
> +    tlb->attr = 0;
> +    tlb->prot = PAGE_VALID | ((PAGE_READ | PAGE_WRITE | PAGE_EXEC) << 4);
> +    tlb->size = 256 * 1024 * 1024;


Is this code really mapping the entire 32bit addr space as the comment says?


> +    tlb->EPN = va & TARGET_PAGE_MASK;
> +    tlb->RPN = pa & TARGET_PAGE_MASK;
> +    tlb->PID = 0;
> +}
> +
>  static void mpc8544ds_init(ram_addr_t ram_size,
>                           const char *boot_device,
>                           const char *kernel_filename,
> @@ -188,6 +215,10 @@ static void mpc8544ds_init(ram_addr_t ram_size,
>          exit(1);
>      }
>  
> +    /* XXX register timer? */
> +    ppc_emb_timers_init(env, 400000000, PPC_INTERRUPT_DECR);
> +    ppc_dcr_init(env, NULL, NULL);
> +
>      /* Fixup Memory size on a alignment boundary */
>      ram_size &= ~(RAM_SIZES_ALIGN - 1);
>  
> @@ -265,6 +296,9 @@ static void mpc8544ds_init(ram_addr_t ram_size,
>  
>      /* If we're loading a kernel directly, we must load the device tree too. */
>      if (kernel_filename) {
> +#ifndef CONFIG_FDT
> +        cpu_abort(env, "Compiled without FDT support - can't load kernel\n");
> +#endif
>          dt_base = (kernel_size + DTC_LOAD_PAD) & ~DTC_PAD_MASK;
>          if (mpc8544_load_device_tree(dt_base, ram_size,
>                      initrd_base, initrd_size, kernel_cmdline) < 0) {
> @@ -272,11 +306,13 @@ static void mpc8544ds_init(ram_addr_t ram_size,
>              exit(1);
>          }
>  
> +        cpu_reset(env);
> +
>          /* Set initial guest state. */
>          env->gpr[1] = (16<<20) - 8;
>          env->gpr[3] = dt_base;
>          env->nip = entry;
> -        /* XXX we currently depend on KVM to create some initial TLB entries. */
> +        mmubooke_create_initial_mapping(env, 0, 0);
>      }
>  

Should the cpu_reset & friends maybe be done from a qemu_register_reset
registerd callback?

Cheers