Re: [Qemu-devel] [RfC PATCH] vga: add mmio bar to standard vga

[Avi Kivity <avi@redhat.com>]

On 09/18/2012 12:51 PM, Gerd Hoffmann wrote:
> This patch adds a mmio bar to the qemu standard vga which allows to
> access the standard vga registers and bochs dispi interface registers
> via mmio.
> 
> diff --git a/hw/vga-pci.c b/hw/vga-pci.c
> index 9abbada..e05e2ef 100644
> --- a/hw/vga-pci.c
> +++ b/hw/vga-pci.c
> @@ -30,9 +30,36 @@
>  #include "qemu-timer.h"
>  #include "loader.h"
>  
> +/*
> + * QEMU Standard VGA -- MMIO area spec.
> + *
> + * Using PCI bar #2, keeping #1 free, which leaves the
> + * door open to upgrade bar #0 to 64bit.
> + *
> + * mmio area layout:
> + *   0x0000 -> 0x03ff  reserved, for possible virtio extension.
> + *   0x0400 -> 0x041f  vga ioports (0x3c0 -> 0x3df), remapped 1:1

Do they support word accesses to set both index and data?

> + *   0x0500 -> 0x0515  bochs dispi interface registers, mapped flat without
> + *                     index/data ports.  Use (index << 1) as offset for
> + *                     (16bit) register access.
> + */

BAR should disappear with -M old.

> +
> +static const MemoryRegionOps pci_vga_ioport_ops = {
> +    .read = pci_vga_ioport_read,
> +    .write = pci_vga_ioport_write,
> +    .valid.min_access_size = 1,
> +    .valid.max_access_size = 4,
> +    .impl.min_access_size = 1,
> +    .impl.max_access_size = 1,
> +    .endianness = DEVICE_LITTLE_ENDIAN,
> +};

Looks like word writes are supported provided the memory API breaks up
writes in little endian order.  Better to make it explicit.



-- 
error compiling committee.c: too many arguments to function