Re: [PATCH v5 1/3] Update linux headers to 6.0-rc1

[Daniel P . Berrangé]

On Mon, Aug 22, 2022 at 05:00:03PM +0200, Michal Prívozník wrote:
> On 8/17/22 04:08, Chenyi Qiang wrote:
> > commit 568035b01cfb107af8d2e4bd2fb9aea22cf5b868
> > 
> > Signed-off-by: Chenyi Qiang <chenyi.qiang@intel.com>
> > ---
> >  include/standard-headers/asm-x86/bootparam.h  |   7 +-
> >  include/standard-headers/drm/drm_fourcc.h     |  73 +++++++-
> >  include/standard-headers/linux/ethtool.h      |  29 +--
> >  include/standard-headers/linux/input.h        |  12 +-
> >  include/standard-headers/linux/pci_regs.h     |  30 ++-
> >  include/standard-headers/linux/vhost_types.h  |  17 +-
> >  include/standard-headers/linux/virtio_9p.h    |   2 +-
> >  .../standard-headers/linux/virtio_config.h    |   7 +-
> >  include/standard-headers/linux/virtio_ids.h   |  14 +-
> >  include/standard-headers/linux/virtio_net.h   |  34 +++-
> >  include/standard-headers/linux/virtio_pci.h   |   2 +
> >  linux-headers/asm-arm64/kvm.h                 |  27 +++
> >  linux-headers/asm-generic/unistd.h            |   4 +-
> >  linux-headers/asm-riscv/kvm.h                 |  22 +++
> >  linux-headers/asm-riscv/unistd.h              |   3 +-
> >  linux-headers/asm-s390/kvm.h                  |   1 +
> >  linux-headers/asm-x86/kvm.h                   |  33 ++--
> >  linux-headers/asm-x86/mman.h                  |  14 --
> >  linux-headers/linux/kvm.h                     | 172 +++++++++++++++++-
> >  linux-headers/linux/userfaultfd.h             |  10 +-
> >  linux-headers/linux/vduse.h                   |  47 +++++
> >  linux-headers/linux/vfio.h                    |   4 +-
> >  linux-headers/linux/vfio_zdev.h               |   7 +
> >  linux-headers/linux/vhost.h                   |  35 +++-
> >  24 files changed, 523 insertions(+), 83 deletions(-)
> > 
> 
> 
> > diff --git a/linux-headers/asm-x86/kvm.h b/linux-headers/asm-x86/kvm.h
> > index bf6e96011d..46de10a809 100644
> > --- a/linux-headers/asm-x86/kvm.h
> > +++ b/linux-headers/asm-x86/kvm.h
> > @@ -198,13 +198,13 @@ struct kvm_msrs {
> >     __u32 nmsrs; /* number of msrs in entries */
> >     __u32 pad;
> >  
> > -   struct kvm_msr_entry entries[0];
> > +   struct kvm_msr_entry entries[];
> >  };
> >  
> 
> I don't think it's this simple. I think this needs to go hand in hand with 
> kvm_arch_get_supported_msr_feature().
> 
> Also, this breaks clang build:
> 
> clang -m64 -mcx16 -Ilibqemu-x86_64-softmmu.fa.p -I. -I.. -Itarget/i386 
> -I../target/i386 -Iqapi -Itrace -Iui -Iui/shader -I/usr/include/pixman-1 
> -I/usr/include/spice-server -I/usr/include/spice-1 -I/usr/include/glib-2.0 
> -I/usr/lib64/glib-2.0/include -fcolor-diagnostics -Wall -Winvalid-pch -Werror 
> -std=gnu11 -O0 -g -isystem /home/zippy/work/qemu/qemu.git/linux-headers 
> -isystem linux-headers -iquote . -iquote /home/zippy/work/qemu/qemu.git 
> -iquote /home/zippy/work/qemu/qemu.git/include -iquote 
> /home/zippy/work/qemu/qemu.git/tcg/i386 -pthread -D_GNU_SOURCE 
> -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes 
> -Wredundant-decls -Wundef -Wwrite-strings -Wmissing-prototypes 
> -fno-strict-aliasing -fno-common -fwrapv -Wold-style-definition -Wtype-limits 
> -Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers -Wempty-body 
> -Wnested-externs -Wendif-labels -Wexpansion-to-defined 
> -Wno-initializer-overrides -Wno-missing-include-dirs 
> -Wno-shift-negative-value -Wno-string-plus-int -Wno-typedef-redefinition 
> -Wno-tautological-type-limit-compare -Wno-psabi -fstack-protector-strong -O0 
> -ggdb -fPIE -isystem../linux-headers -isystemlinux-headers -DNEED_CPU_H 
> '-DCONFIG_TARGET="x86_64-softmmu-config-target.h"' 
> '-DCONFIG_DEVICES="x86_64-softmmu-config-devices.h"' -MD -MQ 
> libqemu-x86_64-softmmu.fa.p/target_i386_kvm_kvm.c.o -MF 
> libqemu-x86_64-softmmu.fa.p/target_i386_kvm_kvm.c.o.d -o 
> libqemu-x86_64-softmmu.fa.p/target_i386_kvm_kvm.c.o -c 
> ../target/i386/kvm/kvm.c
> ../target/i386/kvm/kvm.c:470:25: error: field 'info' with variable sized type 
> 'struct kvm_msrs' not at the end of a struct or class is a GNU extension 
> [-Werror,-Wgnu-variable-sized-type-not-at-end]
>         struct kvm_msrs info;
>                         ^
> ../target/i386/kvm/kvm.c:1701:27: error: field 'cpuid' with variable sized 
> type 'struct kvm_cpuid2' not at the end of a struct or class is a GNU 
> extension [-Werror,-Wgnu-variable-sized-type-not-at-end]
>         struct kvm_cpuid2 cpuid;
>                           ^
> ../target/i386/kvm/kvm.c:2868:25: error: field 'info' with variable sized 
> type 'struct kvm_msrs' not at the end of a struct or class is a GNU extension 
> [-Werror,-Wgnu-variable-sized-type-not-at-end]
>         struct kvm_msrs info;
>                         ^
> 3 errors generated.

We're perfectly OK with using GNU extensions  in QEMU (eg the g_auto stuff),
so IMHO just set  -Wno-gnu-variable-sized-type-not-at-end to turn off this
warning that's only relevant to people striving for fully portable C
code.


With regards,
Daniel
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