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Re: [Qemu-devel] [PATCH] cirrus_vga: adding sanity check for vram size
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH] cirrus_vga: adding sanity check for vram size |
Date: |
Fri, 9 May 2014 12:18:08 +0100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
* address@hidden (address@hidden) wrote:
> From: Gonglei <address@hidden>
>
> when configure a invalid vram size for cirrus card, such as less
> 2 MB, which will crash qemu. Follow the real hardware, the cirrus
> card has 4 MB video memory. Also for backward compatibility, accept
> 8 MB and 16 MB vram size.
virt-manager/libvirt seems to default to 9 MByte of Vram for cirrus,
so this would break a lot of setups.
Looking at datasheets on the web seems to say the chips actually went
down to 1 MB or less.
I think before doing this change, it would be good to understand where
the weird 9MB in libvirt/virt-manager came from, and what the limits of
the emulator/drivers are.
Also, is there something broken at the moment - why make the change?
Dave
> Signed-off-by: Gonglei <address@hidden>
> ---
> For isa cirrus vga device, its' init function has been droped at
> commit db895a1e6a97e919f9b86d60c969377357b05066. I have no idea how adding
> check on isa_cirrus_vga device. Any ideas? Thanks.
>
> hw/display/cirrus_vga.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c
> index d1afc76..5fec068 100644
> --- a/hw/display/cirrus_vga.c
> +++ b/hw/display/cirrus_vga.c
> @@ -2959,6 +2959,13 @@ static int pci_cirrus_vga_initfn(PCIDevice *dev)
> PCIDeviceClass *pc = PCI_DEVICE_GET_CLASS(dev);
> int16_t device_id = pc->device_id;
>
> + /* follow real hardware, cirrus card emulated has 4 MB video memory.
> + Also accept 8 MB/16 MB for backward compatibility. */
> + if (s->vga.vram_size_mb != 4 || s->vga.vram_size_mb != 8 ||
> + s->vga.vram_size_mb != 16) {
> + error_report("Invalid cirrus_vga ram size '%u'\n",
> s->vga.vram_size_mb);
> + return -1;
> + }
> /* setup VGA */
> vga_common_init(&s->vga, OBJECT(dev), true);
> cirrus_init_common(s, OBJECT(dev), device_id, 1, pci_address_space(dev),
> --
> 1.7.12.4
>
>
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
Re: [Qemu-devel] [PATCH] cirrus_vga: adding sanity check for vram size,
Dr. David Alan Gilbert <=
Re: [Qemu-devel] [PATCH] cirrus_vga: adding sanity check for vram size, Paolo Bonzini, 2014/05/09
Re: [Qemu-devel] [PATCH] cirrus_vga: adding sanity check for vram size, Eric Blake, 2014/05/12