Re: [Qemu-devel] [PATCH v2 1/3] leon3: add a little bootloader

[Mark Cave-Ayland]

On 03/05/2019 08:53, Mark Cave-Ayland wrote:

> On 25/04/2019 13:18, KONRAD Frederic wrote:
> 
>> This adds a little bootloader to the leon3_machine when a ram image is
>> given through the kernel parameter and no bios are provided:
>>   * The UART transmiter is enabled.
>>   * The TIMER is initialized.
>>
>> Reviewed-by: Fabien Chouteau <address@hidden>
>> Reviewed-by: Philippe Mathieu-Daudé <address@hidden>
>> Signed-off-by: KONRAD Frederic <address@hidden>
>> ---
>>  hw/sparc/leon3.c | 84 
>> +++++++++++++++++++++++++++++++++++++++++++++++++-------
>>  1 file changed, 74 insertions(+), 10 deletions(-)
>>
>> diff --git a/hw/sparc/leon3.c b/hw/sparc/leon3.c
>> index 774639a..f25432c 100644
>> --- a/hw/sparc/leon3.c
>> +++ b/hw/sparc/leon3.c
>> @@ -1,7 +1,7 @@
>>  /*
>>   * QEMU Leon3 System Emulator
>>   *
>> - * Copyright (c) 2010-2011 AdaCore
>> + * Copyright (c) 2010-2019 AdaCore
>>   *
>>   * Permission is hereby granted, free of charge, to any person obtaining a 
>> copy
>>   * of this software and associated documentation files (the "Software"), to 
>> deal
>> @@ -44,6 +44,8 @@
>>  #define CPU_CLK (40 * 1000 * 1000)
>>  
>>  #define PROM_FILENAME        "u-boot.bin"
>> +#define LEON3_PROM_OFFSET    (0x00000000)
>> +#define LEON3_RAM_OFFSET     (0x40000000)
>>  
>>  #define MAX_PILS 16
>>  
>> @@ -53,6 +55,59 @@ typedef struct ResetData {
>>      target_ulong sp;            /* initial stack pointer */
>>  } ResetData;
>>  
>> +static uint32_t *gen_store_u32(uint32_t *code, hwaddr addr, uint32_t val)
>> +{
>> +    stl_p(code++, 0x82100000); /* mov %g0, %g1                */
>> +    stl_p(code++, 0x84100000); /* mov %g0, %g2                */
>> +    stl_p(code++, 0x03000000 +
>> +      extract32(addr, 10, 22));
>> +                               /* sethi %hi(addr), %g1        */
>> +    stl_p(code++, 0x82106000 +
>> +      extract32(addr, 0, 10));
>> +                               /* or %g1, addr, %g1           */
>> +    stl_p(code++, 0x05000000 +
>> +      extract32(val, 10, 22));
>> +                               /* sethi %hi(val), %g2         */
>> +    stl_p(code++, 0x8410a000 +
>> +      extract32(val, 0, 10));
>> +                               /* or %g2, val, %g2            */
>> +    stl_p(code++, 0xc4204000); /* st %g2, [ %g1 ]             */
>> +
>> +    return code;
>> +}
>> +
>> +/*
>> + * When loading a kernel in RAM the machine is expected to be in a different
>> + * state (eg: initialized by the bootloader). This little code reproduces
>> + * this behavior.
>> + */
>> +static void write_bootloader(CPUSPARCState *env, uint8_t *base,
>> +                             hwaddr kernel_addr)
>> +{
>> +    uint32_t *p = (uint32_t *) base;
>> +
>> +    /* Initialize the UARTs                                        */
>> +    /* *UART_CONTROL = UART_RECEIVE_ENABLE | UART_TRANSMIT_ENABLE; */
>> +    p = gen_store_u32(p, 0x80000108, 3);
>> +
>> +    /* Initialize the TIMER 0                                      */
>> +    /* *GPTIMER_SCALER_RELOAD = 40 - 1;                            */
>> +    p = gen_store_u32(p, 0x80000304, 39);
>> +    /* *GPTIMER0_COUNTER_RELOAD = 0xFFFE;                          */
>> +    p = gen_store_u32(p, 0x80000314, 0xFFFFFFFE);
>> +    /* *GPTIMER0_CONFIG = GPTIMER_ENABLE | GPTIMER_RESTART;        */
>> +    p = gen_store_u32(p, 0x80000318, 3);
>> +
>> +    /* JUMP to the entry point                                     */
>> +    stl_p(p++, 0x82100000); /* mov %g0, %g1 */
>> +    stl_p(p++, 0x03000000 + extract32(kernel_addr, 10, 22));
>> +                            /* sethi %hi(kernel_addr), %g1 */
>> +    stl_p(p++, 0x82106000 + extract32(kernel_addr, 0, 10));
>> +                            /* or kernel_addr, %g1 */
>> +    stl_p(p++, 0x81c04000); /* jmp  %g1 */
>> +    stl_p(p++, 0x01000000); /* nop */
>> +}
>> +
>>  static void main_cpu_reset(void *opaque)
>>  {
>>      ResetData *s   = (ResetData *)opaque;
>> @@ -131,11 +186,12 @@ static void leon3_generic_hw_init(MachineState 
>> *machine)
>>      /* Reset data */
>>      reset_info        = g_malloc0(sizeof(ResetData));
>>      reset_info->cpu   = cpu;
>> -    reset_info->sp    = 0x40000000 + ram_size;
>> +    reset_info->sp    = LEON3_RAM_OFFSET + ram_size;
>>      qemu_register_reset(main_cpu_reset, reset_info);
>>  
>>      /* Allocate IRQ manager */
>> -    grlib_irqmp_create(0x80000200, env, &cpu_irqs, MAX_PILS, 
>> &leon3_set_pil_in);
>> +    grlib_irqmp_create(0x80000200, env, &cpu_irqs, MAX_PILS,
>> +                       &leon3_set_pil_in);
>>  
>>      env->qemu_irq_ack = leon3_irq_manager;
>>  
>> @@ -148,13 +204,13 @@ static void leon3_generic_hw_init(MachineState 
>> *machine)
>>      }
>>  
>>      memory_region_allocate_system_memory(ram, NULL, "leon3.ram", ram_size);
>> -    memory_region_add_subregion(address_space_mem, 0x40000000, ram);
>> +    memory_region_add_subregion(address_space_mem, LEON3_RAM_OFFSET, ram);
>>  
>>      /* Allocate BIOS */
>>      prom_size = 8 * MiB;
>>      memory_region_init_ram(prom, NULL, "Leon3.bios", prom_size, 
>> &error_fatal);
>>      memory_region_set_readonly(prom, true);
>> -    memory_region_add_subregion(address_space_mem, 0x00000000, prom);
>> +    memory_region_add_subregion(address_space_mem, LEON3_PROM_OFFSET, prom);
>>  
>>      /* Load boot prom */
>>      if (bios_name == NULL) {
>> @@ -174,7 +230,7 @@ static void leon3_generic_hw_init(MachineState *machine)
>>      }
>>  
>>      if (bios_size > 0) {
>> -        ret = load_image_targphys(filename, 0x00000000, bios_size);
>> +        ret = load_image_targphys(filename, LEON3_PROM_OFFSET, bios_size);
>>          if (ret < 0 || ret > prom_size) {
>>              error_report("could not load prom '%s'", filename);
>>              exit(1);
>> @@ -198,10 +254,18 @@ static void leon3_generic_hw_init(MachineState 
>> *machine)
>>              exit(1);
>>          }
>>          if (bios_size <= 0) {
>> -            /* If there is no bios/monitor, start the application.  */
>> -            env->pc = entry;
>> -            env->npc = entry + 4;
>> -            reset_info->entry = entry;
>> +            /*
>> +             * If there is no bios/monitor just start the application but 
>> put
>> +             * the machine in an initialized state through a little
>> +             * bootloader.
>> +             */
>> +            uint8_t *bootloader_entry;
>> +
>> +            bootloader_entry = memory_region_get_ram_ptr(prom);
>> +            write_bootloader(env, bootloader_entry, entry);
>> +            env->pc = LEON3_PROM_OFFSET;
>> +            env->npc = LEON3_PROM_OFFSET + 4;
>> +            reset_info->entry = LEON3_PROM_OFFSET;
>>          }
>>      }
> 
> I think this patch is basically okay, however if you don't supply both a 
> kernel and
> bios then you get the slightly enigmatic message below:
> 
> $ ./qemu-system-sparc -M leon3_generic
> qemu-system-sparc: Can't read bios image (null)
> 
> Perhaps add a define for LEON3_BIOS_FILENAME and return that if filename == 
> NULL to
> give a better error message?

Okay I see there is already a PROM_FILENAME that exists and can be used here.


ATB,

Mark.