meson: Revert recent changes to qemu version header handling

This reverts commit ab78ac76f44a1241e76fd32d248df62d83f1ea58.

The change to create the version header in meson.build loses the dependency needed for the header file to be built when it doesn't exist. This means that:

* if you delete the build/qemu-version.h file, an incremental rebuild fails, rather than recreating it

* if you do an incremental rebuild from a build tree that pre-dates ab78ac76f44a, it doesn't have qemu-version.h, and the rebuild fails

Revert the commit so we can think about how we want to address this.

Signed-off-by Peter Maydell <[email protected]>

---
 meson.build               | 29 +++++++++--------------------
 include/qemu/version.h    |  8 --------
 scripts/qemu-version.h.in |  1 -
 scripts/qemu-version.sh   | 25 +++++++++++++++++++++++++
 4 files changed, 34 insertions(+), 29 deletions(-)
 delete mode 100644 scripts/qemu-version.h.in
 create mode 100755 scripts/qemu-version.sh

meson.build +9 -20

index d7bcb581c18..93da3e6f2bd 100644
@@ -78,7 +78,6 @@ have_user = have_linux_user or have_bsd_user
 ############
 
 sh = find_program('sh')
-git = find_program('git', required: false)
 python = import('python').find_installation()
 
 cc = meson.get_compiler('c')

@@ -3561,25 +3560,15 @@ tracetool_depends = files(
   'scripts/tracetool/__init__.py',
 )
 
-qemu_pkgversion = get_option('pkgversion')
-git_describe_version = [git, 'describe', '--match', 'v*', '--dirty']
-if qemu_pkgversion == '' and git.found() and fs.exists('.git') and \
-    run_command(git_describe_version, check: false).returncode() == 0
-  # Refresh the version at build time, so that "make" after a commit updates it.
-  qemu_version = vcs_tag(input: 'scripts/qemu-version.h.in',
-                         output: 'qemu-version.h',
-                         command: git_describe_version,
-                         fallback: '')
-else
-  # Unlike vcs_tag(), which always defines QEMU_PKGVERSION, leave it out if
-  # empty.  include/qemu/version.h then omits the parentheses from
-  # QEMU_FULL_VERSION.
-  qemu_version_data = configuration_data()
-  if qemu_pkgversion != ''
-    qemu_version_data.set_quoted('QEMU_PKGVERSION', qemu_pkgversion)
-  endif
-  qemu_version = configure_file(output: 'qemu-version.h', configuration: qemu_version_data)
-endif
+qemu_version_cmd = [find_program('scripts/qemu-version.sh'),
+                    meson.current_source_dir(),
+                    get_option('pkgversion'), meson.project_version()]
+qemu_version = custom_target('qemu-version.h',
+                             output: 'qemu-version.h',
+                             command: qemu_version_cmd,
+                             capture: true,
+                             build_by_default: true,
+                             build_always_stale: true)
 genh += qemu_version
 
 hxdep = []

include/qemu/version.h +0 -8

index dd0f937f30c..38405495c0e 100644
@@ -7,14 +7,6 @@
 #ifndef QEMU_VERSION_H
 #define QEMU_VERSION_H
 
-/* qemu-version.h defines QEMU_PKGVERSION only if it is not empty.  */
 #include "qemu-version.h"
 
-#ifdef QEMU_PKGVERSION
-#define QEMU_FULL_VERSION QEMU_VERSION " (" QEMU_PKGVERSION ")"
-#else
-#define QEMU_PKGVERSION ""
-#define QEMU_FULL_VERSION QEMU_VERSION
-#endif
-
 #endif

scripts/qemu-version.h.in deleted +0 -1

deleted file mode 100644
index b62d4c22652..00000000000
@@ -1 +0,0 @@
-#define QEMU_PKGVERSION "@VCS_TAG@"

scripts/qemu-version.sh new file +25 -0

new file mode 100755
index 00000000000..3f6e7e6d41d
@@ -0,0 +1,25 @@
+#!/bin/sh
+
+set -eu
+
+dir="$1"
+pkgversion="$2"
+version="$3"
+
+if [ -z "$pkgversion" ]; then
+    cd "$dir"
+    if [ -e .git ]; then
+        pkgversion=$(git describe --match 'v*' --dirty) || :
+    fi
+fi
+
+if [ -n "$pkgversion" ]; then
+    fullversion="$version ($pkgversion)"
+else
+    fullversion="$version"
+fi
+
+cat <<EOF
+#define QEMU_PKGVERSION "$pkgversion"
+#define QEMU_FULL_VERSION "$fullversion"
+EOF

Quoted 6 lines · Peter Maydell

This reverts commit ab78ac76f44a1241e76fd32d248df62d83f1ea58.

The change to create the version header in meson.build loses the dependency needed for the header file to be built when it doesn't exist. This means that:

Quoted 2 lines

* if you delete the build/qemu-version.h file, an incremental rebuild fails, rather than recreating it

That's not what I observe. From current master, file is correctly recreated. Do you still observe a problem with a clean build folder?

The problem seems to be crossing this commit, which we can't do anything about since it's there.

$ git log --oneline -1
f71afb409a8 Merge tag 'pull-loongarch-20261105' of
https://github.com/bibo-mao/qemu into staging
$ rm -rf build/arm && mkdir build/arm && (cd build/arm &&
'../../configure'

'--target-list=arm-softmmu,aarch64-softmmu,arm-linux-user,aarch64-linux-user,aarch64_be-linux-user'
'--cc=ccache gcc' '--with-pkgversion=pm215' '--enable-debug'
'--enable-docs') && make -C build/arm -j20
[...]
$ make -C build/arm -j20
make: Entering directory '/home/pm215/qemu/build/arm'
[1/35] Generating tests/include/QAPI test (include) with a custom command
make: Leaving directory '/home/pm215/qemu/build/arm'

$ make -C build/arm -j20
make: Entering directory '/home/pm215/qemu/build/arm'
[1/27] Compiling C object qga/qemu-ga.p/main.c.o
FAILED: qga/qemu-ga.p/main.c.o
/usr/bin/ccache gcc -m64 -Iqga/qemu-ga.p -Iqga -I../../qga -I. -Iqapi

(quoted diff) +0 -14

-Itrace -Iui -Iui/shader -I/usr/include/glib-2.0
-I/usr/lib/x86_64-linux-gnu/glib-2.0/include -fdiagnostics-color=auto
-Wall -Winvalid-pch -Werror -std=gnu11 -O0 -g -mcx16 -msse2
-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
-fno-strict-aliasing -fno-common -fwrapv -ftrivial-auto-var-init=zero
-fzero-call-used-regs=used-gpr -fstack-protector-strong -Wempty-body
-Wendif-labels -Wexpansion-to-defined -Wformat-overflow=2
-Wformat-security -Wformat-y2k -Wignored-qualifiers
-Wimplicit-fallthrough=2 -Winit-self -Wmissing-format-attribute
-Wmissing-prototypes -Wnested-externs -Wold-style-declaration
-Wold-style-definition -Wredundant-decls -Wshadow=local
-Wstrict-prototypes -Wtype-limits -Wundef -Wvla -Wwrite-strings
-Wno-missing-include-dirs -Wno-psabi -Wno-shift-negative-value
-isystem /home/pm215/qemu/linux-headers -isystem linux-headers -iquote

. -iquote /home/pm215/qemu -iquote /home/pm215/qemu/include -iquote /home/pm215/qemu/host/include/x86_64 -iquote /home/pm215/qemu/host/include/generic -iquote /home/pm215/qemu/tcg/x86_64 -pthread -fPIE -MD -MQ qga/qemu-ga.p/main.c.o -MF qga/qemu-ga.p/main.c.o.d -o qga/qemu-ga.p/main.c.o -c ../../qga/main.c
In file included from ../../qga/main.c:33:
/home/pm215/qemu/include/qemu/version.h:11:10: fatal error:
qemu-version.h: No such file or directory
11 | #include "qemu-version.h"

      |          ^~~~~~~~~~~~~~~~

compilation terminated.
[etc]

Quoted 8 lines · Pierrick Bouvier

Quoted 6 lines · Peter Maydell

This reverts commit ab78ac76f44a1241e76fd32d248df62d83f1ea58.

The change to create the version header in meson.build loses the dependency needed for the header file to be built when it doesn't exist. This means that:

Quoted 5 lines

Quoted 2 lines

* if you delete the build/qemu-version.h file, an incremental rebuild fails, rather than recreating it

That's not what I observe. From current master, file is correctly recreated. Do you still observe a problem with a clean build folder?

Yes.

$ git log --oneline -1
f71afb409a8 Merge tag 'pull-loongarch-20261105' of
https://github.com/bibo-mao/qemu into staging
$ rm -rf build/arm && mkdir build/arm && (cd build/arm &&
'../../configure'
'--target-list=arm-softmmu,aarch64-softmmu,arm-linux-user,aarch64-linux-user,aarch64_be-linux-user'
'--cc=ccache gcc' '--with-pkgversion=pm215' '--enable-debug'
'--enable-docs') && make -C build/arm -j20
[...]
$ make -C build/arm -j20
make: Entering directory '/home/pm215/qemu/build/arm'
[1/35] Generating tests/include/QAPI test (include) with a custom command
make: Leaving directory '/home/pm215/qemu/build/arm'
$ make -C build/arm -j20
make: Entering directory '/home/pm215/qemu/build/arm'
[1/27] Compiling C object qga/qemu-ga.p/main.c.o
FAILED: qga/qemu-ga.p/main.c.o
/usr/bin/ccache gcc -m64 -Iqga/qemu-ga.p -Iqga -I../../qga -I. -Iqapi

(quoted diff) +0 -14

-Itrace -Iui -Iui/shader -I/usr/include/glib-2.0
-I/usr/lib/x86_64-linux-gnu/glib-2.0/include -fdiagnostics-color=auto
-Wall -Winvalid-pch -Werror -std=gnu11 -O0 -g -mcx16 -msse2
-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
-fno-strict-aliasing -fno-common -fwrapv -ftrivial-auto-var-init=zero
-fzero-call-used-regs=used-gpr -fstack-protector-strong -Wempty-body
-Wendif-labels -Wexpansion-to-defined -Wformat-overflow=2
-Wformat-security -Wformat-y2k -Wignored-qualifiers
-Wimplicit-fallthrough=2 -Winit-self -Wmissing-format-attribute
-Wmissing-prototypes -Wnested-externs -Wold-style-declaration
-Wold-style-definition -Wredundant-decls -Wshadow=local
-Wstrict-prototypes -Wtype-limits -Wundef -Wvla -Wwrite-strings
-Wno-missing-include-dirs -Wno-psabi -Wno-shift-negative-value
-isystem /home/pm215/qemu/linux-headers -isystem linux-headers -iquote

. -iquote /home/pm215/qemu -iquote /home/pm215/qemu/include -iquote /home/pm215/qemu/host/include/x86_64 -iquote /home/pm215/qemu/host/include/generic -iquote /home/pm215/qemu/tcg/x86_64 -pthread -fPIE -MD -MQ qga/qemu-ga.p/main.c.o -MF qga/qemu-ga.p/main.c.o.d -o qga/qemu-ga.p/main.c.o -c ../../qga/main.c
In file included from ../../qga/main.c:33:
/home/pm215/qemu/include/qemu/version.h:11:10: fatal error:
qemu-version.h: No such file or directory
11 | #include "qemu-version.h"

      |          ^~~~~~~~~~~~~~~~

compilation terminated.
[etc]

I have run into this problem about a dozen times this week with different build trees and different git branches, and it is very annoying.

Quoted 2 lines

The problem seems to be crossing this commit, which we can't do anything about since it's there.

Yeah, it's going to be a broken git bisect for that part of history, which is unavoidable. But the current state of git is (a) broken and (b) not clearly what we actually want, per the other thread.

-- PMM

Quoted 71 lines · Peter Maydell

Quoted 8 lines · Pierrick Bouvier

Quoted 6 lines · Peter Maydell

This reverts commit ab78ac76f44a1241e76fd32d248df62d83f1ea58.

The change to create the version header in meson.build loses the dependency needed for the header file to be built when it doesn't exist. This means that:

Quoted 5 lines

Quoted 2 lines

* if you delete the build/qemu-version.h file, an incremental rebuild fails, rather than recreating it

That's not what I observe. From current master, file is correctly recreated. Do you still observe a problem with a clean build folder?

Yes.

$ git log --oneline -1
f71afb409a8 Merge tag 'pull-loongarch-20261105' of
https://github.com/bibo-mao/qemu into staging
$ rm -rf build/arm && mkdir build/arm && (cd build/arm &&
'../../configure'
'--target-list=arm-softmmu,aarch64-softmmu,arm-linux-user,aarch64-linux-user,aarch64_be-linux-user'
'--cc=ccache gcc' '--with-pkgversion=pm215' '--enable-debug'
'--enable-docs') && make -C build/arm -j20
[...]
$ make -C build/arm -j20
make: Entering directory '/home/pm215/qemu/build/arm'
[1/35] Generating tests/include/QAPI test (include) with a custom command
make: Leaving directory '/home/pm215/qemu/build/arm'
$ make -C build/arm -j20
make: Entering directory '/home/pm215/qemu/build/arm'
[1/27] Compiling C object qga/qemu-ga.p/main.c.o
FAILED: qga/qemu-ga.p/main.c.o
/usr/bin/ccache gcc -m64 -Iqga/qemu-ga.p -Iqga -I../../qga -I. -Iqapi

(quoted diff) +0 -14

-Itrace -Iui -Iui/shader -I/usr/include/glib-2.0
-I/usr/lib/x86_64-linux-gnu/glib-2.0/include -fdiagnostics-color=auto
-Wall -Winvalid-pch -Werror -std=gnu11 -O0 -g -mcx16 -msse2
-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
-fno-strict-aliasing -fno-common -fwrapv -ftrivial-auto-var-init=zero
-fzero-call-used-regs=used-gpr -fstack-protector-strong -Wempty-body
-Wendif-labels -Wexpansion-to-defined -Wformat-overflow=2
-Wformat-security -Wformat-y2k -Wignored-qualifiers
-Wimplicit-fallthrough=2 -Winit-self -Wmissing-format-attribute
-Wmissing-prototypes -Wnested-externs -Wold-style-declaration
-Wold-style-definition -Wredundant-decls -Wshadow=local
-Wstrict-prototypes -Wtype-limits -Wundef -Wvla -Wwrite-strings
-Wno-missing-include-dirs -Wno-psabi -Wno-shift-negative-value
-isystem /home/pm215/qemu/linux-headers -isystem linux-headers -iquote

. -iquote /home/pm215/qemu -iquote /home/pm215/qemu/include -iquote /home/pm215/qemu/host/include/x86_64 -iquote /home/pm215/qemu/host/include/generic -iquote /home/pm215/qemu/tcg/x86_64 -pthread -fPIE -MD -MQ qga/qemu-ga.p/main.c.o -MF qga/qemu-ga.p/main.c.o.d -o qga/qemu-ga.p/main.c.o -c ../../qga/main.c
In file included from ../../qga/main.c:33:
/home/pm215/qemu/include/qemu/version.h:11:10: fatal error:
qemu-version.h: No such file or directory
11 | #include "qemu-version.h"

      |          ^~~~~~~~~~~~~~~~

compilation terminated.
[etc]

I have run into this problem about a dozen times this week with different build trees and different git branches, and it is very annoying.

Quoted 2 lines

The problem seems to be crossing this commit, which we can't do anything about since it's there.

Quoted 6 lines

Yeah, it's going to be a broken git bisect for that part of history, which is unavoidable. But the current state of git is (a) broken and (b) not clearly what we actually want, per the other thread.

-- PMM

I see, the missing bit I didn't use is '--with-pkgversion=pm215'. Without it, it works fine.

Any reason you use it for dev builds?

Seems to be something related to releases, which probably won't use incremental builds.

Regards,
Pierrick

I see, the missing bit I didn't use is '--with-pkgversion=pm215'. Without it, it works fine.

Any reason you use it for dev builds?

This patchset is two git reverts, to revert ab78ac76f44a124 and fc35f24387703da. Those commits try to move the handling of version.h to entirely within the meson file with no external script, but unfortunately if you do that then there is no dependency information about it passed to ninja, so the file isn't recreated if it's missing. In particular this breaks incremental builds from a build tree that pre-dates those two commits.

There's been some on-list discussion:
https://lore.kernel.org/qemu-devel/[email protected]/
Since it's not clear how we want to proceed, I'm posting this as the "revert to the situation we had before", so we can discuss what we want to do with a bit more leisure.