Re: [Qemu-devel] [PATCH] get roms more room.

[Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>]

On 28.03.2009 00:48, Glauber Costa wrote:
> This patch increases by 50 % the size available for option roms.
> The main motivator is that some roms grew bigger than the 64k we
> currently allocate for them (Hey, it's 2009!)
>
> One example is the gpxe project, that produces some roms with 69k,
> 70k, etc. The space proposed by this patch actually makes it as
> big as 84k. Probably still a fit for some time.
>
> But there is no free lunch. This space must come from somewhere,
> and we take it from vga rom space. Currently, our vga roms are
> around 35k in size. With this patch, option rom space will begin
> just after vga ends, aligned to the next 2k boundary.
>
> Technicaly, we could do the same with the uper space (the bios itself),
> but since bochs bios is already 128 k in size, I don't see an
> urgent need to do it.
>
> Signed-off-by: Glauber Costa <glommer@redhat.com>
>   

I really like the patch, but I have one questions I can't answer because
I'm not familiar enough with the Qemu and Bochs BIOS codebase. You can
find it as inline comment.

Since the patch seems to do what I want, it is
Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>

If a Signed-off-by line is preferred, I can send that instead.

> ---
>  hw/pc.c |   27 +++++++++++++++++----------
>  1 files changed, 17 insertions(+), 10 deletions(-)
>
> diff --git a/hw/pc.c b/hw/pc.c
> index 69f25f3..07a9791 100644
> --- a/hw/pc.c
> +++ b/hw/pc.c
> @@ -763,7 +763,7 @@ static void pc_init1(ram_addr_t ram_size, int vga_ram_size,
>  {
>      char buf[1024];
>      int ret, linux_boot, i;
> -    ram_addr_t ram_addr, vga_ram_addr, bios_offset, vga_bios_offset;
> +    ram_addr_t ram_addr, vga_ram_addr, bios_offset, vga_bios_offset, option_rom_start;
>      ram_addr_t below_4g_mem_size, above_4g_mem_size = 0;
>      int bios_size, isa_bios_size, vga_bios_size;
>      PCIBus *pci_bus;
> @@ -774,6 +774,7 @@ static void pc_init1(ram_addr_t ram_size, int vga_ram_size,
>      int index;
>      BlockDriverState *hd[MAX_IDE_BUS * MAX_IDE_DEVS];
>      BlockDriverState *fd[MAX_FD];
> +    int using_vga = cirrus_vga_enabled || std_vga_enabled || vmsvga_enabled;
>  
>      if (ram_size >= 0xe0000000 ) {
>          above_4g_mem_size = ram_size - 0xe0000000;
> @@ -856,7 +857,11 @@ static void pc_init1(ram_addr_t ram_size, int vga_ram_size,
>          exit(1);
>      }
>  
> -    if (cirrus_vga_enabled || std_vga_enabled || vmsvga_enabled) {
> +    /* No point in placing option roms before this address, since bochs bios
> +     * will only start looking for it at 0xc8000 */
> +    option_rom_start = 0xc8000;
> +
> +    if (using_vga) {
>          /* VGA BIOS load */
>          if (cirrus_vga_enabled) {
>              snprintf(buf, sizeof(buf), "%s/%s", bios_dir, VGABIOS_CIRRUS_FILENAME);
> @@ -874,9 +879,12 @@ vga_bios_error:
>              fprintf(stderr, "qemu: could not load VGA BIOS '%s'\n", buf);
>              exit(1);
>          }
> +	/* Round up vga bios size to the next 2k boundary */
> +	vga_bios_size = (vga_bios_size + 2047) & ~2047;
>   

If vga_bios_size ever shrinks below 30k, the option ROMs will start
below 0xc8000 and the Bochs BIOS won't find them. Is that right?

> +	option_rom_start = 0xc0000 + vga_bios_size;
>  
>          /* setup basic memory access */
> -        cpu_register_physical_memory(0xc0000, 0x10000,
> +        cpu_register_physical_memory(0xc0000, vga_bios_size,
>                                       vga_bios_offset | IO_MEM_ROM);
>      }
>  
> @@ -892,14 +900,14 @@ vga_bios_error:
>          ram_addr_t option_rom_offset;
>          int size, offset;
>  
> -        offset = 0;
> +        offset = option_rom_start;
>          if (linux_boot) {
>              option_rom_offset = qemu_ram_alloc(TARGET_PAGE_SIZE);
>              load_linux(phys_ram_base + option_rom_offset,
>                         kernel_filename, initrd_filename, kernel_cmdline);
> -            cpu_register_physical_memory(0xd0000, TARGET_PAGE_SIZE,
> +            cpu_register_physical_memory(option_rom_start, TARGET_PAGE_SIZE,
>                                           option_rom_offset | IO_MEM_ROM);
> -            offset = TARGET_PAGE_SIZE;
> +            offset += TARGET_PAGE_SIZE;
>          }
>  
>          for (i = 0; i < nb_option_roms; i++) {
> @@ -909,18 +917,17 @@ vga_bios_error:
>                          option_rom[i]);
>                  exit(1);
>              }
> -            if (size > (0x10000 - offset))
> +            if (size > (0xe0000  - offset))
>                  goto option_rom_error;
>              option_rom_offset = qemu_ram_alloc(size);
>              ret = load_image(option_rom[i], phys_ram_base + option_rom_offset);
>              if (ret != size) {
>              option_rom_error:
> -                fprintf(stderr, "Too many option ROMS\n");
> +                fprintf(stderr, "Could not fit %soption roms in available space\n", using_vga ? "VGA bios and " : "");
>                  exit(1);
>              }
>              size = (size + 4095) & ~4095;
> -            cpu_register_physical_memory(0xd0000 + offset,
> -                                         size, option_rom_offset | IO_MEM_ROM);
> +            cpu_register_physical_memory(offset, size, option_rom_offset | IO_MEM_ROM);
>              offset += size;
>          }
>      }
>   

Regards,
Carl-Daniel

-- 
http://www.hailfinger.org/