Re: [Qemu-devel] [PATCH] isapc: Fix segfault during initialization

[Anthony Liguori <anthony@codemonkey.ws>]

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On 01/14/2012 07:12 AM, Jan Kiszka wrote:
> From: Jan Kiszka<jan.kiszka@siemens.com>
>
> Linking the RTC device state to the PIIX does not belong into the
> common path that is shared with the isapc. QEMU crashes otherwise.
>
> Signed-off-by: Jan Kiszka<jan.kiszka@siemens.com>

Does isapc actually work for you?  I tried to write a qemu-test test case 
(attached below) to help prevent future regressions.  I can reproduce your SEGV 
but with your patch applied, I get no output (not even the BIOS runs).

Here's the command line.  Even a simple 'qemu-system-x86_64 -M isapc' reproduces it:

/home/anthony/build/qemu/x86_64-softmmu/qemu-system-x86_64 -kernel 
bin/vmlinuz-3.0 -initrd .tmp-3510/initramfs-3510.img.gz -append console=ttyS0 
seed=24689 -M isapc -pidfile .tmp-3510/pidfile-3510.pid -qmp 
unix:.tmp-3510/qmpsock-3510.sock,server,nowait

Regards,

Anthony Liguori


> ---
>   hw/pc_piix.c |   22 +++++++++++-----------
>   1 files changed, 11 insertions(+), 11 deletions(-)
>
> diff --git a/hw/pc_piix.c b/hw/pc_piix.c
> index b70431f..3aea3cc 100644
> --- a/hw/pc_piix.c
> +++ b/hw/pc_piix.c
> @@ -201,6 +201,17 @@ static void pc_init1(MemoryRegion *system_memory,
>           }
>           idebus[0] = qdev_get_child_bus(&dev->qdev, "ide.0");
>           idebus[1] = qdev_get_child_bus(&dev->qdev, "ide.1");
> +
> +        /* FIXME there's some major spaghetti here.  Somehow we create the
> +         * devices on the PIIX before we actually create it.  We create the
> +         * PIIX3 deep in the recess of the i440fx creation too and then lose
> +         * the DeviceState.
> +         *
> +         * For now, let's "fix" this by making judicious use of paths.  This
> +         * is not generally the right way to do this.
> +         */
> +        qdev_property_add_child(qdev_resolve_path("/i440fx/piix3", NULL),
> +                                "rtc", (DeviceState *)rtc_state, NULL);
>       } else {
>           for(i = 0; i<  MAX_IDE_BUS; i++) {
>               ISADevice *dev;
> @@ -211,17 +222,6 @@ static void pc_init1(MemoryRegion *system_memory,
>           }
>       }
>
> -    /* FIXME there's some major spaghetti here.  Somehow we create the devices
> -     * on the PIIX before we actually create it.  We create the PIIX3 deep in
> -     * the recess of the i440fx creation too and then lose the DeviceState.
> -     *
> -     * For now, let's "fix" this by making judicious use of paths.  This is not
> -     * generally the right way to do this.
> -     */
> -
> -    qdev_property_add_child(qdev_resolve_path("/i440fx/piix3", NULL),
> -                            "rtc", (DeviceState *)rtc_state, NULL);
> -
>       audio_init(isa_bus, pci_enabled ? pci_bus : NULL);
>
>       pc_cmos_init(below_4g_mem_size, above_4g_mem_size, boot_device,


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