Re: [PATCH 2/2] hw/uefi: add pcap support

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 26/11/25 15:25, Gerd Hoffmann wrote:
> Add pcapfile property to uevi-vars-* devices, allowing to write out a
> capture of the communication traffic between uefi firmware and qemu.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>   include/hw/uefi/var-service.h | 10 ++++
>   hw/uefi/var-service-core.c    |  7 +++
>   hw/uefi/var-service-pcap.c    | 94 +++++++++++++++++++++++++++++++++++
>   hw/uefi/var-service-sysbus.c  |  1 +
>   hw/uefi/meson.build           |  1 +
>   roms/edk2                     |  2 +-
>   6 files changed, 114 insertions(+), 1 deletion(-)
>   create mode 100644 hw/uefi/var-service-pcap.c


> diff --git a/hw/uefi/var-service-pcap.c b/hw/uefi/var-service-pcap.c
> new file mode 100644
> index 000000000000..879eee4699a3
> --- /dev/null
> +++ b/hw/uefi/var-service-pcap.c
> @@ -0,0 +1,94 @@
> +/*
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +#include "qemu/osdep.h"
> +#include "qemu/error-report.h"
> +#include "qemu/pcap.h"
> +#include "system/dma.h"
> +
> +#include "hw/uefi/var-service.h"
> +
> +#define LINKTYPE_EDK2_MM  302
> +
> +#define SNAPLEN   (64 * 1024)
> +#define TYPE_RESET       0x01
> +#define TYPE_REQUEST     0x02
> +#define TYPE_REPLY       0x03
> +
> +static void uefi_vars_pcap_header(FILE *fp)
> +{

static const

> +    struct pcap_hdr header = {
> +        .magic_number  = PCAP_MAGIC,
> +        .version_major = PCAP_MAJOR,
> +        .version_minor = PCAP_MINOR,
> +        .snaplen       = SNAPLEN,
> +        .network       = LINKTYPE_EDK2_MM,
> +    };
> +
> +    fwrite(&header, sizeof(header), 1, fp);
> +    fflush(fp);
> +}


> +void uefi_vars_pcap_init(uefi_vars_state *uv)
> +{
> +    int fd;
> +
> +    if (!uv->pcapfile) {
> +        return;
> +    }
> +
> +    fd = qemu_open_old(uv->pcapfile,
> +                       O_CREAT | O_WRONLY | O_TRUNC | O_BINARY, 0666);

Consider qemu_create() to help Markus' tree-wide cleanup.

> +    if (fd < 0) {
> +        warn_report("open %s: %s", uv->pcapfile, strerror(errno));
> +        return;
> +    }
> +
> +    uv->pcapfp = fdopen(fd, "wb");
> +    uefi_vars_pcap_header(uv->pcapfp);
> +}


> diff --git a/roms/edk2 b/roms/edk2
> index 4dfdca63a934..46548b1adac8 160000
> --- a/roms/edk2
> +++ b/roms/edk2
> @@ -1 +1 @@
> -Subproject commit 4dfdca63a93497203f197ec98ba20e2327e4afe4
> +Subproject commit 46548b1adac82211d8d11da12dd914f41e7aa775

Unrelated change I presume.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>