[SeaBIOS] [PATCHv2] pci: load memory window setup from host

[Kevin O'Connor]

On Tue, Apr 30, 2013 at 09:34:55AM +0300, Michael S. Tsirkin wrote:
> Load memory window setup for pci from host.
> This makes it possible for host to make sure
> setup matches hardware exactly: especially important
> for when ACPI tables are loaded from host.
> This will also make it easier to add more chipsets
> down the road.

I'm struggling to understand this patch.  I think the code may need
some refactoring.

[...]
> --- a/src/pciinit.c
> +++ b/src/pciinit.c
> @@ -13,6 +13,7 @@
>  #include "config.h" // CONFIG_*
>  #include "memmap.h" // add_e820
>  #include "paravirt.h" // RamSize
> +#include "byteorder.h" // le64_to_cpu
>  #include "dev-q35.h"
>  
>  /* PM Timer ticks per second (HZ) */
> @@ -61,6 +62,13 @@ struct pci_bus {
>      struct pci_device *bus_dev;
>  };
>  
> +struct pci_mem {
> +	u64 start32;

SeaBIOS uses spaces; not tabs.

[...]
>  void i440fx_mem_addr_setup(struct pci_device *dev, void *arg)
>  {
> +    if (arg)
> +	/* use supplied memory */;

Huh?

[...]
>  /****************************************************************
>   * Main setup code
>   ****************************************************************/
> -
>  void
>  pci_setup(void)
>  {
> @@ -823,25 +868,39 @@ pci_setup(void)
>      dprintf(1, "=== PCI device probing ===\n");
>      pci_probe_devices();
>  
> -    pcimem_start = RamSize;
> -    pci_bios_init_platform();
> +    struct pci_mem *mem = pci_mem_get();
> +
> +    if (mem) {
> +        pcimem_start = mem->start32;
> +        pcimem_end = mem->end32;
> +        pcimem64_start = mem->start64;
> +        pcimem64_end = mem->end64;
> +    } else {
> +        pcimem_start = RamSize;
> +    }
> +
> +    pci_bios_init_platform(mem);
>  
>      dprintf(1, "=== PCI new allocation pass #1 ===\n");
>      struct pci_bus *busses = malloc_tmp(sizeof(*busses) * (MaxPCIBus + 1));
>      if (!busses) {
>          warn_noalloc();
> -        return;
> +        goto done;
>      }
>      memset(busses, 0, sizeof(*busses) * (MaxPCIBus + 1));
>      if (pci_bios_check_devices(busses))
> -        return;
> +        goto done;
>  
>      dprintf(1, "=== PCI new allocation pass #2 ===\n");
> -    pci_bios_map_devices(busses);
> +    pci_bios_map_devices(busses, mem);
>  
>      pci_bios_init_devices();
>  
>      free(busses);
>  
>      pci_enable_default_vga();
> +
> +done:
> +    if (mem)
> +        free(mem);

I don't understand why dynamic memory is used, and I don't understand
why "mem" is passed around and inspected in so many places.

-Kevin