Re: [Qemu-devel] [PATCH 6/6] [S390] Add firmware code

[Aurelien Jarno]

On Thu, Apr 01, 2010 at 06:42:41PM +0200, Alexander Graf wrote:
> This patch adds a firmware blob to the S390 target. The blob is a simple
> implementation of a virtio client that tries to read the second stage
> bootloader from sectors described as of offset 0x20 in the MBR.
> 
> In combination with an updated zipl this allows for booting from virtio
> block devices. This firmware is built from the same sources as the second
> stage bootloader. You can find the zipl patch to build both here:
> 
> http://alex.csgraf.de/qemu/0001-Zipl-VirtIO-bootloader-code.patch

I am not fully comfortable introducing a binary firmware based on a
patch posted on a website. I see two options:
- Get your patch merged into ZIPL, so that we can build the firmware
  directly from the ZIPL sources
- Add the patch to the pc-bios/ directory

Also it would be nice to update pc-bios/README to provide details about
the ZIPL version used to build pc-bios/s390-zipl.rom.

> Signed-off-by: Alexander Graf <address@hidden>
> ---
>  hw/s390-virtio.c      |   20 ++++++++++++++++++++
>  pc-bios/s390-zipl.rom |  Bin 0 -> 2448 bytes
>  2 files changed, 20 insertions(+), 0 deletions(-)
>  create mode 100755 pc-bios/s390-zipl.rom
> 
> diff --git a/hw/s390-virtio.c b/hw/s390-virtio.c
> index c36a8b2..91a3065 100644
> --- a/hw/s390-virtio.c
> +++ b/hw/s390-virtio.c
> @@ -52,6 +52,10 @@
>  #define INITRD_PARM_SIZE                0x010410UL
>  #define PARMFILE_START                  0x001000UL
>  
> +#define ZIPL_START                   0x001000UL
> +#define ZIPL_LOAD_ADDR                       0x001000UL
> +#define ZIPL_FILENAME                        "s390-zipl.rom"
> +
>  #define MAX_BLK_DEVS                    10
>  
>  static VirtIOS390Bus *s390_bus;
> @@ -140,6 +144,8 @@ static void s390_init(ram_addr_t ram_size,
>      ram_addr_t kernel_size = 0;
>      ram_addr_t initrd_offset;
>      ram_addr_t initrd_size = 0;
> +    ram_addr_t bios_size = 0;
> +    char *bios_filename;
>      int i;
>  
>      /* XXX we only work on KVM for now */
> @@ -178,6 +184,20 @@ static void s390_init(ram_addr_t ram_size,
>      env->halted = 0;
>      env->exception_index = 0;
>  
> +    /* Load zipl bootloader */
> +    if (bios_name == NULL)
> +        bios_name = ZIPL_FILENAME;

You are missing curly braces here.

> +    bios_filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
> +    bios_size = load_image(bios_filename, qemu_get_ram_ptr(ZIPL_LOAD_ADDR));
> +
> +    if ((long)bios_size < 0) {
> +        hw_error("could not load bootloader '%s'\n", bios_name);
> +    }
> +
> +    env->psw.addr = ZIPL_START;
> +    env->psw.mask = 0x0000000180000000ULL;
> +

This probably has to be put in a reset handler so that this address is
reloaded upon reboot.

Also do you really want to make the firmware mandatory? What about a
warning and falling back to the direct kernel boot instead (if provided), 
as it is already now. Some other machines are doing that.

>      if (kernel_filename) {
>          kernel_size = load_image(kernel_filename, qemu_get_ram_ptr(0));
>  
> diff --git a/pc-bios/s390-zipl.rom b/pc-bios/s390-zipl.rom
> new file mode 100755
> index 
> 0000000000000000000000000000000000000000..0f1b26afd5ad530035cdc6fbe285bae278ad5983
> GIT binary patch
> literal 2448
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> address@hidden@address@hidden&iCivAlhRl(SPsMDeTHB-3oRqREw_}
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> 
> literal 0
> HcmV?d00001
> 
> -- 
> 1.6.0.2
> 
> 
> 
> 

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
address@hidden                 http://www.aurel32.net