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From: Ladi Prosek <lprosek@redhat.com>
Date: Tue, 3 Oct 2017 13:49:24 +0200
Message-ID: <CABdb736D975ai2N_o9Df5UCn5de6ohrxtajTmtT-B8smbDDvKw@mail.gmail.com>
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Subject: Re: [Qemu-devel] [PATCH 07/43] windbg: added chardev
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To: Mihail Abakumov <mikhail.abakumov@ispras.ru>
Cc: qemu-devel <qemu-devel@nongnu.org>, sw@weilnetz.de, Pavel Dovgalyuk <dovgaluk@ispras.ru>, Roman Kagan <rkagan@virtuozzo.com>, Paolo Bonzini <pbonzini@redhat.com>, "Denis V. Lunev" <den@openvz.org>

On Tue, Sep 26, 2017 at 1:04 PM, Mihail Abakumov
<mikhail.abakumov@ispras.ru> wrote:
> Added chardev for listening to windbg. Target device is a parameter in the '-windbg' option.
>
> Signed-off-by: Mihail Abakumov <mikhail.abakumov@ispras.ru>
> Signed-off-by: Pavel Dovgalyuk <dovgaluk@ispras.ru>
> Signed-off-by: Dmitriy Koltunov <koltunov@ispras.ru>
> ---
>  windbgstub.c |   26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
>
> diff --git a/windbgstub.c b/windbgstub.c
> index 60a380c213..378d1b911f 100755
> --- a/windbgstub.c
> +++ b/windbgstub.c
> @@ -10,6 +10,7 @@
>   */
>
>  #include "qemu/osdep.h"
> +#include "qapi/error.h"
>  #include "chardev/char.h"
>  #include "chardev/char-fe.h"
>  #include "exec/windbgstub.h"
> @@ -18,12 +19,26 @@
>  typedef struct WindbgState {
>      bool is_loaded;
>
> +    CharBackend chr;
> +
>      uint32_t ctrl_packet_id;
>      uint32_t data_packet_id;
>  } WindbgState;
>
>  static WindbgState *windbg_state;
>
> +static int windbg_chr_can_receive(void *opaque)
> +{
> +    return PACKET_MAX_SIZE;
> +}
> +
> +static void windbg_chr_receive(void *opaque, const uint8_t *buf, int size)
> +{
> +    if (windbg_state->is_loaded) {
> +        /* T0D0: parse data */
> +    }
> +}
> +
>  static void windbg_exit(void)
>  {
>      g_free(windbg_state);
> @@ -31,6 +46,8 @@ static void windbg_exit(void)
>
>  int windbg_server_start(const char *device)
>  {
> +    Chardev *chr = NULL;
> +
>      if (windbg_state) {
>          WINDBG_ERROR("Multiple instances are not supported");
>          exit(1);
> @@ -40,6 +57,15 @@ int windbg_server_start(const char *device)
>      windbg_state->ctrl_packet_id = RESET_PACKET_ID;
>      windbg_state->data_packet_id = INITIAL_PACKET_ID;
>
> +    chr = qemu_chr_new_noreplay(WINDBG, device);
> +    if (!chr) {

This should generate error output. Passing "-windbg bogus" makes QEMU
exit silently.
-gdb seems to have the same problem.

> +        return -1;
> +    }
> +
> +    qemu_chr_fe_init(&windbg_state->chr, chr, &error_abort);
> +    qemu_chr_fe_set_handlers(&windbg_state->chr, windbg_chr_can_receive,
> +                             windbg_chr_receive, NULL, NULL, NULL, NULL, true);
> +
>      atexit(windbg_exit);
>      return 0;
>  }
>