Re: [Qemu-devel] [PATCH v2] qtest: ask endianness of the target in qtest_init()

[David Gibson]

On Fri, Oct 07, 2016 at 12:14:27PM +0200, Laurent Vivier wrote:
> The target endianness is not deduced anymore from
> the architecture name but asked directly to the guest,
> using a new qtest command: "endianness". As it can't
> change (this is the value of TARGET_WORDS_BIGENDIAN),
> we store it to not have to ask every time we want to
> know if we have to byte-swap a value.
> 
> Signed-off-by: Laurent Vivier <address@hidden>
> CC: Greg Kurz <address@hidden>
> CC: David Gibson <address@hidden>
> CC: Peter Maydell <address@hidden>

Reviewed-by: David Gibson <address@hidden>

As with Greg, I think this is an improvement over the current
situation, even though I still have concerns about other things
related to this.

> ---
> v2:
> - move the "endianness" command to a function and
>   don't move the qtest_init()/qtest_quit() functions
> 
>  qtest.c                   |  7 +++++
>  tests/libqos/virtio-pci.c |  2 +-
>  tests/libqtest.c          | 68 
> ++++++++++++++++-------------------------------
>  tests/libqtest.h          | 16 ++++++++---
>  tests/virtio-blk-test.c   |  2 +-
>  5 files changed, 45 insertions(+), 50 deletions(-)
> 
> diff --git a/qtest.c b/qtest.c
> index 22482cc..b53b39c 100644
> --- a/qtest.c
> +++ b/qtest.c
> @@ -537,6 +537,13 @@ static void qtest_process_command(CharDriverState *chr, 
> gchar **words)
>  
>          qtest_send_prefix(chr);
>          qtest_send(chr, "OK\n");
> +    } else if (strcmp(words[0], "endianness") == 0) {
> +        qtest_send_prefix(chr);
> +#if defined(TARGET_WORDS_BIGENDIAN)
> +        qtest_sendf(chr, "OK big\n");
> +#else
> +        qtest_sendf(chr, "OK little\n");
> +#endif
>  #ifdef TARGET_PPC64
>      } else if (strcmp(words[0], "rtas") == 0) {
>          uint64_t res, args, ret;
> diff --git a/tests/libqos/virtio-pci.c b/tests/libqos/virtio-pci.c
> index 18b92b9..6e005c1 100644
> --- a/tests/libqos/virtio-pci.c
> +++ b/tests/libqos/virtio-pci.c
> @@ -86,7 +86,7 @@ static uint64_t qvirtio_pci_config_readq(QVirtioDevice *d, 
> uint64_t addr)
>      int i;
>      uint64_t u64 = 0;
>  
> -    if (qtest_big_endian()) {
> +    if (target_big_endian()) {
>          for (i = 0; i < 8; ++i) {
>              u64 |= (uint64_t)qpci_io_readb(dev->pdev,
>                                  (void *)(uintptr_t)addr + i) << (7 - i) * 8;
> diff --git a/tests/libqtest.c b/tests/libqtest.c
> index 6f6bdf1..d4e6bff 100644
> --- a/tests/libqtest.c
> +++ b/tests/libqtest.c
> @@ -37,6 +37,7 @@ struct QTestState
>      bool irq_level[MAX_IRQ];
>      GString *rx;
>      pid_t qemu_pid;  /* our child QEMU process */
> +    bool big_endian;
>  };
>  
>  static GHookList abrt_hooks;
> @@ -47,6 +48,8 @@ static struct sigaction sigact_old;
>      g_assert_cmpint(ret, !=, -1); \
>  } while (0)
>  
> +static int qtest_query_target_endianness(QTestState *s);
> +
>  static int init_socket(const char *socket_path)
>  {
>      struct sockaddr_un addr;
> @@ -209,6 +212,10 @@ QTestState *qtest_init(const char *extra_args)
>          kill(s->qemu_pid, SIGSTOP);
>      }
>  
> +    /* ask endianness of the target */
> +
> +    s->big_endian = qtest_query_target_endianness(s);
> +
>      return s;
>  }
>  
> @@ -342,6 +349,20 @@ redo:
>      return words;
>  }
>  
> +static int qtest_query_target_endianness(QTestState *s)
> +{
> +    gchar **args;
> +    int big_endian;
> +
> +    qtest_sendf(s, "endianness\n");
> +    args = qtest_rsp(s, 1);
> +    g_assert(strcmp(args[1], "big") == 0 || strcmp(args[1], "little") == 0);
> +    big_endian = strcmp(args[1], "big") == 0;
> +    g_strfreev(args);
> +
> +    return big_endian;
> +}
> +
>  typedef struct {
>      JSONMessageParser parser;
>      QDict *response;
> @@ -886,50 +907,7 @@ char *hmp(const char *fmt, ...)
>      return ret;
>  }
>  
> -bool qtest_big_endian(void)
> +bool qtest_big_endian(QTestState *s)
>  {
> -    const char *arch = qtest_get_arch();
> -    int i;
> -
> -    static const struct {
> -        const char *arch;
> -        bool big_endian;
> -    } endianness[] = {
> -        { "aarch64", false },
> -        { "alpha", false },
> -        { "arm", false },
> -        { "cris", false },
> -        { "i386", false },
> -        { "lm32", true },
> -        { "m68k", true },
> -        { "microblaze", true },
> -        { "microblazeel", false },
> -        { "mips", true },
> -        { "mips64", true },
> -        { "mips64el", false },
> -        { "mipsel", false },
> -        { "moxie", true },
> -        { "or32", true },
> -        { "ppc", true },
> -        { "ppc64", true },
> -        { "ppcemb", true },
> -        { "s390x", true },
> -        { "sh4", false },
> -        { "sh4eb", true },
> -        { "sparc", true },
> -        { "sparc64", true },
> -        { "unicore32", false },
> -        { "x86_64", false },
> -        { "xtensa", false },
> -        { "xtensaeb", true },
> -        {},
> -    };
> -
> -    for (i = 0; endianness[i].arch; i++) {
> -        if (strcmp(endianness[i].arch, arch) == 0) {
> -            return endianness[i].big_endian;
> -        }
> -    }
> -
> -    return false;
> +    return s->big_endian;
>  }
> diff --git a/tests/libqtest.h b/tests/libqtest.h
> index f7402e0..4be1f77 100644
> --- a/tests/libqtest.h
> +++ b/tests/libqtest.h
> @@ -410,6 +410,14 @@ int64_t qtest_clock_step(QTestState *s, int64_t step);
>  int64_t qtest_clock_set(QTestState *s, int64_t val);
>  
>  /**
> + * qtest_big_endian:
> + * @s: QTestState instance to operate on.
> + *
> + * Returns: True if the architecture under test has a big endian 
> configuration.
> + */
> +bool qtest_big_endian(QTestState *s);
> +
> +/**
>   * qtest_get_arch:
>   *
>   * Returns: The architecture for the QEMU executable under test.
> @@ -874,12 +882,14 @@ static inline int64_t clock_set(int64_t val)
>  }
>  
>  /**
> - * qtest_big_endian:
> + * target_big_endian:
>   *
>   * Returns: True if the architecture under test has a big endian 
> configuration.
>   */
> -bool qtest_big_endian(void);
> -
> +static inline bool target_big_endian(void)
> +{
> +    return qtest_big_endian(global_qtest);
> +}
>  
>  QDict *qmp_fd_receive(int fd);
>  void qmp_fd_sendv(int fd, const char *fmt, va_list ap);
> diff --git a/tests/virtio-blk-test.c b/tests/virtio-blk-test.c
> index 3c4fecc..0506917 100644
> --- a/tests/virtio-blk-test.c
> +++ b/tests/virtio-blk-test.c
> @@ -125,7 +125,7 @@ static inline void virtio_blk_fix_request(QVirtioBlkReq 
> *req)
>      bool host_endian = false;
>  #endif
>  
> -    if (qtest_big_endian() != host_endian) {
> +    if (target_big_endian() != host_endian) {
>          req->type = bswap32(req->type);
>          req->ioprio = bswap32(req->ioprio);
>          req->sector = bswap64(req->sector);

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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