Re: [PATCH v2] Add -build-info and -build-info-json CLI arguments

[Manos Pitsidianakis <manos.pitsidianakis@linaro.org>]

Hello Daniel,

On Mon, 23 Sep 2024 19:45, "Daniel P. Berrangé" <berrange@redhat.com> wrote:
>On Mon, Sep 23, 2024 at 09:05:24AM +0300, Manos Pitsidianakis wrote:
>> Add -build-info and -build-info-json CLI arguments for human and machine
>> readable output of build/compile-time configuration data. The source for
>> this data is the meson generated config-host.h.
>> 
>> This information is mainly of interest to developers and other folk who
>> deal with many different builds of QEMU and need a way to properly
>> differentiate them.
>> 
>> Because there's always the chance someone will want to consume an
>> interface programmatically, also add a -json option that does the same
>> but outputs a machine-readable JSON object.
>
>This turns our build system configuration information into a
>defacto public API, and while its using JSON, it isn't yusing
>QAPI.
>
>To some degree we leak our build system config names externally
>because the "if" stanzas in the QAPI schema get copied into the
>docs.
>
>Overall though I don't think we should be exposing this build
>config infomation externally. We've had many times, particularly
>with testing, where people have wanted to access CONFIG_XXX info
>about a QEMU binary, but IIRC we've always steered people towards
>querying for the actual feature they want, rather than looking
>at CONFIG_XXX settings.
>
>ie, look a query-audiodevs to discover what audio baxckends are
>built-in, don't look for CONFIG_XXX settings related to audio.
>If there are gaps in information we can query from QMP, we should
>aim to close those gaps.
>
>IOW, I don't think we should expose this build info info in either
>human readable or machine readable format.

QAPI/QMP is not the perspective of this patch, this is for people who 
use custom-built (i.e. not from a distro) binaries and want to be able 
to identify how it was built. Launching a binary to query stuff is 
unnecessarily complex for this task, and the info is not generally 
interesting to the API consumers as you said.


Manos

>
>> 
>> Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
>> ---
>> Changes in v2:
>> - Fixed alignment of command and documentation in -h output.
>> - Link to v1: https://lore.kernel.org/r/20240923-feature-build-info-cli-v1-1-e8c42d845390@linaro.org
>> ---
>> Notes:
>> Sample output:
>> 
>> $ ./qemu-system-aarch64 -build-info
>> ./qemu-system-aarch64 version 9.1.50 (v9.0.0-3444-g8d988656d8) build information
>> 
>>   configuration key          key value
>>   -----------------          ---------
>>   accept4                    
>>   af_vsock                   
>>   asan_iface_fiber           
>>   atomic64                   
>>   attr                       
>>   audio_alsa                 
>>   audio_drivers              pa,sndio,oss
>>   audio_oss                  
>>   audio_pa                   
>>   audio_pipewire             
>>   audio_sdl                  
>>   audio_sndio                
>>   avx2_opt                   
>>   avx512bw_opt               
>>   bdrv_ro_whitelist          
>>   bdrv_rw_whitelist          
>>   bindir                     /usr/local/bin
>>   blkzoned                   
>>   brlapi                     
>>   capstone                   
>>   clock_adjtime              
>>   close_range                
>>   coroutine_pool             
>>   cpuid_h                    
>>   curl                       
>>   curses                     
>>   dbus_display               
>>   debug_graph_lock           
>>   debug_mutex                
>>   debug_tcg                  
>>   dup3                       
>>   ebpf                       
>>   epoll                      
>>   epoll_create1              
>>   eventfd                    
>>   fallocate                  
>>   fallocate_punch_hole       
>>   fallocate_zero_range       
>>   fdatasync                  
>>   fdt                        
>>   fiemap                     
>>   fsfreeze                   
>>   fstrim                     
>>   fuse                       
>>   fuse_lseek                 
>>   gbm                        
>>   getauxval                  
>>   getcpu                     
>>   getrandom                  
>>   gettid                     
>>   gio                        
>>   gnutls                     
>>   gnutls_crypto              
>>   gtk                        
>>   hexagon_idef_parser        
>>   host_dsosuf                .so
>>   iasl                       /bin/iasl
>>   inotify                    
>>   inotify1                   
>>   int128                     
>>   int128_type                
>>   iovec                      
>>   keyutils                   
>>   kvm_targets                i386-softmmu,x86_64-softmmu
>>   l2tpv3                     
>>   libdw                      
>>   libudev                    
>>   linux                      
>>   linux_io_uring             
>>   linux_magic_h              
>>   madvise                    
>>   malloc_trim                
>>   memalign                   
>>   memfd                      
>>   opengl                     
>>   open_by_handle             
>>   pixman                     
>>   plugin                     
>>   png                        
>>   posix                      
>>   posix_fallocate            
>>   posix_madvise              
>>   posix_memalign             
>>   ppoll                      
>>   prctl_pr_set_timerslack    
>>   preadv                     
>>   prefix                     /usr/local
>>   pthread_affinity_np        
>>   pthread_setname_np_w_tid   
>>   qemu_confdir               /usr/local/etc/qemu
>>   qemu_datadir               /usr/local/share/qemu
>>   qemu_desktopdir            /usr/local/share/applications
>>   qemu_firmwarepath          /usr/local/share/qemu-firmware
>>   qemu_helperdir             /usr/local/libexec
>>   qemu_icondir               /usr/local/share/icons
>>   qemu_localedir             /usr/local/share/locale
>>   qemu_localstatedir         /var/local
>>   qemu_moddir                /usr/local/lib/x86_64-linux-gnu/qemu
>>   qom_cast_debug             
>>   relocatable                
>>   replication                
>>   rtnetlink                  
>>   sdl                        
>>   seccomp                    
>>   seccomp_sysrawrc           
>>   secret_keyring             
>>   selinux                    
>>   sendfile                   
>>   setns                      
>>   signalfd                   
>>   slirp                      
>>   smbd_command               /usr/sbin/smbd
>>   splice                     
>>   statx                      
>>   statx_mnt_id               
>>   syncfs                     
>>   sync_file_range            
>>   sysconfdir                 /usr/local/etc
>>   sysmacros                  
>>   tasn1                      
>>   tcg                        1
>>   timerfd                    
>>   tls_priority               NORMAL
>>   tpm                        
>>   trace_file                 trace
>>   trace_log                  
>>   usbfs                      
>>   usb_libusb                 
>>   valgrind_h                 
>>   valloc                     
>>   vduse_blk_export           
>>   vhost                      
>>   vhost_crypto               
>>   vhost_kernel               
>>   vhost_net                  
>>   vhost_net_user             
>>   vhost_net_vdpa             
>>   vhost_user                 
>>   vhost_user_blk_server      
>>   vhost_vdpa                 
>>   virtfs                     
>>   vnc                        
>>   vnc_jpeg                   
>>   vte                        
>>   x11                        
>>   xen_backend                
>>   xen_ctrl_interface_version 41700
>>   xkbcommon                  
>>   zstd                       
>>   blk_zone_rep_capacity      
>>   btrfs_h                    
>>   copy_file_range            
>>   drm_h                      
>>   fsxattr                    
>>   getifaddrs                 
>>   host_block_device          
>>   ipproto_mptcp              
>>   mlockall                   
>>   openpty                    
>>   pty_h                      
>>   strchrnul                  
>>   struct_stat_st_atim        
>>   system_function            
>>   utmpx                      
>>   virgl_d3d_info_ext         
>>   host_x86_64                1
>>   qemu_version               9.1.50
>>   qemu_version_major         9
>>   qemu_version_micro         50
>>   qemu_version_minor         1
>> 
>> To: qemu-devel@nongnu.org
>> Cc: "Cleber Rosa" <crosa@redhat.com>
>> Cc: "Daniel P. Berrangé" <berrange@redhat.com>
>> Cc: "John Snow" <jsnow@redhat.com>
>> Cc: "Marc-André Lureau" <marcandre.lureau@redhat.com>
>> Cc: "Paolo Bonzini" <pbonzini@redhat.com>
>> Cc: "Alex Bennée" <alex.bennee@linaro.org>
>> Cc: "Gustavo Romero" <gustavo.romero@linaro.org>
>> Cc: "Peter Maydell" <peter.maydell@linaro.org>
>> Cc: "Philippe Mathieu-Daudé" <philmd@linaro.org>
>> Cc: "Pierrick Bouvier" <pierrick.bouvier@linaro.org>
>> Cc: "Richard Henderson" <richard.henderson@linaro.org>
>> Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
>> ---
>>  meson.build               | 15 +++++++-
>>  qemu-options.hx           | 15 ++++++++
>>  scripts/build_info_gen.py | 91 +++++++++++++++++++++++++++++++++++++++++++++++
>>  system/vl.c               | 41 +++++++++++++++++++++
>>  4 files changed, 161 insertions(+), 1 deletion(-)
>> 
>> diff --git a/meson.build b/meson.build
>> index 10464466ff..eff2ee323a 100644
>> --- a/meson.build
>> +++ b/meson.build
>> @@ -3292,7 +3292,20 @@ endif
>>  # Generated sources #
>>  #####################
>>  
>> -genh += configure_file(output: 'config-host.h', configuration: config_host_data)
>> +config_host_h = configure_file(output: 'config-host.h', configuration: config_host_data)
>> +genh += config_host_h
>> +
>> +build_info_h = custom_target('build-info.h',
>> +                             output: 'build-info.h',
>> +                             command: [
>> +                               find_program('scripts/build_info_gen.py'),
>> +                               '--config-headers',
>> +                               config_host_h
>> +                             ],
>> +                             capture: true,
>> +                             build_by_default: true,
>> +                             build_always_stale: true)
>> +genh += build_info_h
>>  
>>  hxtool = find_program('scripts/hxtool')
>>  shaderinclude = find_program('scripts/shaderinclude.py')
>> diff --git a/qemu-options.hx b/qemu-options.hx
>> index d94e2cbbae..6a32e0624f 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -24,6 +24,21 @@ SRST
>>      Display version information and exit
>>  ERST
>>  
>> +DEF("build-info", 0, QEMU_OPTION_build_info,
>> +    "-build-info     display build information of executable and exit\n", QEMU_ARCH_ALL)
>> +SRST
>> +``-build-info``
>> +    Display build information of executable and exit
>> +ERST
>> +
>> +DEF("build-info-json", 0, QEMU_OPTION_build_info_json,
>> +    "-build-info-json\n"
>> +    "                dump build information of executable in JSON format and exit\n", QEMU_ARCH_ALL)
>> +SRST
>> +``-build-info-json``
>> +    Dump build information of executable in JSON format and exit
>> +ERST
>> +
>>  DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
>>      "-machine [type=]name[,prop[=value][,...]]\n"
>>      "                selects emulated machine ('-machine help' for list)\n"
>> diff --git a/scripts/build_info_gen.py b/scripts/build_info_gen.py
>> new file mode 100755
>> index 0000000000..37a9421651
>> --- /dev/null
>> +++ b/scripts/build_info_gen.py
>> @@ -0,0 +1,91 @@
>> +#!/usr/bin/env python3
>> +
>> +"""
>> +Generate build information header, build-info.h,
>> +for output of -build-info* command line arguments.
>> +
>> +SPDX-FileContributor: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
>> +SPDX-FileCopyrightText: 2024 Linaro Ltd.
>> +SPDX-License-Identifier: GPL-2.0-or-later
>> +"""
>> +
>> +# Formatted with black --line-length 80 scripts/build-info-gen.py
>> +
>> +import argparse
>> +import logging
>> +
>> +
>> +def generate_key_val(header: str) -> str:
>> +    # pylint: disable=missing-function-docstring
>> +
>> +    with open(header, encoding="utf-8") as cfg:
>> +        config = [l.split()[1:] for l in cfg if l.startswith("#define")]
>> +
>> +    for cfg in config:
>> +        if cfg[0].startswith("HAVE_"):
>> +            yield (cfg[0].removeprefix("HAVE_").lower(), None)
>> +            continue
>> +        yield (
>> +            cfg[0].removeprefix("CONFIG_").lower(),
>> +            (
>> +                cfg[1]
>> +                if len(cfg) == 2
>> +                else "".join(cfg[1:]).replace('"', "") if len(cfg) > 2 else None
>> +            ),
>> +        )
>> +
>> +
>> +def main() -> None:
>> +    # pylint: disable=missing-function-docstring
>> +    parser = argparse.ArgumentParser()
>> +    parser.add_argument("-v", "--verbose", action="store_true")
>> +    parser.add_argument(
>> +        "--config-headers",
>> +        metavar="CONFIG_HEADER",
>> +        action="append",
>> +        dest="config_headers",
>> +        help="paths to configuration host C headers (*.h files)",
>> +        required=False,
>> +        default=[],
>> +    )
>> +    args = parser.parse_args()
>> +    if args.verbose:
>> +        logging.basicConfig(level=logging.ERROR)
>> +    logging.debug("args: %s", args)
>> +    print(
>> +        """// @generated by scripts/build-info-gen.py
>> +
>> +#include <stddef.h>"""
>> +    )
>> +    print(
>> +        """static struct build_info_t {
>> +    const char *key;
>> +    const char *value;
>> +} BUILD_INFO[] = {"""
>> +    )
>> +    total = 0
>> +    header_width = 0
>> +    for header in args.config_headers:
>> +        for key, val in generate_key_val(header):
>> +            total += 1
>> +            header_width = max(header_width, len(key))
>> +            print(
>> +                '{"',
>> +                key,
>> +                '", "',
>> +                val.strip('"').strip(",").strip('"') if val else "",
>> +                '"},',
>> +                sep="",
>> +            )
>> +    print("};")
>> +    print("\nstatic size_t BUILD_INFO_SIZE = ", total, ";", sep="")
>> +    print(
>> +        "static unsigned int BUILD_INFO_HEADER_WIDTH = ",
>> +        header_width,
>> +        ";",
>> +        sep="",
>> +    )
>> +
>> +
>> +if __name__ == "__main__":
>> +    main()
>> diff --git a/system/vl.c b/system/vl.c
>> index fe547ca47c..5266b85d22 100644
>> --- a/system/vl.c
>> +++ b/system/vl.c
>> @@ -908,6 +908,41 @@ static void help(int exitcode)
>>      exit(exitcode);
>>  }
>>  
>> +static void build_info(const char *execname, bool as_json)
>> +{
>> +#include "build-info.h"
>> +    if (as_json) {
>> +        printf("{\n");
>> +        for (size_t i = 0; i + 1 < BUILD_INFO_SIZE ; i++) {
>> +            printf("\"%s\":\"%s\",\n",
>> +                   BUILD_INFO[i].key,
>> +                   BUILD_INFO[i].value);
>> +        }
>> +        if (BUILD_INFO_SIZE > 0) {
>> +            printf("\"%s\":\"%s\"\n",
>> +                   BUILD_INFO[BUILD_INFO_SIZE - 1].key,
>> +                   BUILD_INFO[BUILD_INFO_SIZE - 1].value);
>> +        }
>> +        printf("}\n");
>> +    } else {
>> +        printf("%s version "
>> +               QEMU_FULL_VERSION
>> +               " build information\n\n", execname ?:"QEMU");
>> +        printf("  %-*s key value\n",
>> +               BUILD_INFO_HEADER_WIDTH,
>> +               "configuration key");
>> +        printf("  %-*s ---------\n",
>> +               BUILD_INFO_HEADER_WIDTH,
>> +               "-----------------");
>> +        for (size_t i = 0; i < BUILD_INFO_SIZE ; i++) {
>> +            printf("  %-*s %s\n",
>> +                   BUILD_INFO_HEADER_WIDTH,
>> +                   BUILD_INFO[i].key,
>> +                   BUILD_INFO[i].value);
>> +        }
>> +    }
>> +}
>> +
>>  enum {
>>  
>>  #define DEF(option, opt_arg, opt_enum, opt_help, arch_mask)     \
>> @@ -3019,6 +3054,12 @@ void qemu_init(int argc, char **argv)
>>                  version();
>>                  exit(0);
>>                  break;
>> +            case QEMU_OPTION_build_info:
>> +                /* fallthrough */
>> +            case QEMU_OPTION_build_info_json:
>> +                build_info(argv[0], popt->index != QEMU_OPTION_build_info);
>> +                exit(0);
>> +                break;
>>              case QEMU_OPTION_m:
>>                  opts = qemu_opts_parse_noisily(qemu_find_opts("memory"), optarg, true);
>>                  if (opts == NULL) {
>> 
>> ---
>> base-commit: 01dc65a3bc262ab1bec8fe89775e9bbfa627becb
>> change-id: 20240922-feature-build-info-cli-c9e08e34c34b
>> 
>> --
>> γαῖα πυρί μιχθήτω
>> 
>
>With regards,
>Daniel
>-- 
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