Re: [Qemu-devel] [PATCH] hw: Nuke hw_compat_4_0_1 and pc_compat_4_0_1

[Michael S. Tsirkin]

On Fri, Jun 14, 2019 at 03:09:02PM +0200, Greg Kurz wrote:
> Commit c87759ce876a fixed a regression affecting pc-q35 machines by
> introducing a new pc-q35-4.0.1 machine version to be used instead
> of pc-q35-4.0. The only purpose was to revert the default behaviour
> of not using split irqchip, but the change also introduced the usual
> hw_compat and pc_compat bits, and wired them for pc-q35 only.
> 
> This raises questions when it comes to add new compat properties for
> 4.0* machine versions of any architecture. Where to add them ? In
> 4.0, 4.0.1 or both ? Error prone. Another possibility would be to teach
> all other architectures about 4.0.1. This solution isn't satisfying,
> especially since this is a pc-q35 specific issue.
> 
> It turns out that the split irqchip default is handled in the machine
> option function and doesn't involve compat lists at all.
> 
> Drop all the 4.0.1 compat lists and use the 4.0 ones instead in the 4.0.1
> machine option function.
> 
> Move the compat props that were added to the 4.0.1 since c87759ce876a to
> 4.0.
> 
> Even if only hw_compat_4_0_1 had an impact on other architectures,
> drop pc_compat_4_0_1 as well for consistency.
> 
> Fixes: c87759ce876a "q35: Revert to kernel irqchip"
> Suggested-by: Dr. David Alan Gilbert <address@hidden>
> Signed-off-by: Greg Kurz <address@hidden>

Reviewed-by: Michael S. Tsirkin <address@hidden>

Paolo are you merging this?

> ---
>  hw/core/machine.c    |    5 +----
>  hw/i386/pc.c         |    3 ---
>  hw/i386/pc_q35.c     |   12 ++++++++----
>  include/hw/boards.h  |    3 ---
>  include/hw/i386/pc.h |    3 ---
>  5 files changed, 9 insertions(+), 17 deletions(-)
> 
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index 84ebb8d24701..ea5a01aa49bc 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -24,16 +24,13 @@
>  #include "hw/pci/pci.h"
>  #include "hw/mem/nvdimm.h"
>  
> -GlobalProperty hw_compat_4_0_1[] = {
> +GlobalProperty hw_compat_4_0[] = {
>      { "VGA",            "edid", "false" },
>      { "secondary-vga",  "edid", "false" },
>      { "bochs-display",  "edid", "false" },
>      { "virtio-vga",     "edid", "false" },
>      { "virtio-gpu-pci", "edid", "false" },
>  };
> -const size_t hw_compat_4_0_1_len = G_N_ELEMENTS(hw_compat_4_0_1);
> -
> -GlobalProperty hw_compat_4_0[] = {};
>  const size_t hw_compat_4_0_len = G_N_ELEMENTS(hw_compat_4_0);
>  
>  GlobalProperty hw_compat_3_1[] = {
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 2c5446b0951e..1a1935825ad2 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -111,9 +111,6 @@ struct hpet_fw_config hpet_cfg = {.count = UINT8_MAX};
>  /* Physical Address of PVH entry point read from kernel ELF NOTE */
>  static size_t pvh_start_addr;
>  
> -GlobalProperty pc_compat_4_0_1[] = {};
> -const size_t pc_compat_4_0_1_len = G_N_ELEMENTS(pc_compat_4_0_1);
> -
>  GlobalProperty pc_compat_4_0[] = {};
>  const size_t pc_compat_4_0_len = G_N_ELEMENTS(pc_compat_4_0);
>  
> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> index dcddc6466200..57232aed6b6c 100644
> --- a/hw/i386/pc_q35.c
> +++ b/hw/i386/pc_q35.c
> @@ -378,8 +378,13 @@ static void pc_q35_4_0_1_machine_options(MachineClass *m)
>  {
>      pc_q35_4_1_machine_options(m);
>      m->alias = NULL;
> -    compat_props_add(m->compat_props, hw_compat_4_0_1, hw_compat_4_0_1_len);
> -    compat_props_add(m->compat_props, pc_compat_4_0_1, pc_compat_4_0_1_len);
> +    /*
> +     * This is the default machine for the 4.0-stable branch. It is basically
> +     * a 4.0 that doesn't use split irqchip by default. It MUST hence apply 
> the
> +     * 4.0 compat props.
> +     */
> +    compat_props_add(m->compat_props, hw_compat_4_0, hw_compat_4_0_len);
> +    compat_props_add(m->compat_props, pc_compat_4_0, pc_compat_4_0_len);
>  }
>  
>  DEFINE_Q35_MACHINE(v4_0_1, "pc-q35-4.0.1", NULL,
> @@ -390,8 +395,7 @@ static void pc_q35_4_0_machine_options(MachineClass *m)
>      pc_q35_4_0_1_machine_options(m);
>      m->default_kernel_irqchip_split = true;
>      m->alias = NULL;
> -    compat_props_add(m->compat_props, hw_compat_4_0, hw_compat_4_0_len);
> -    compat_props_add(m->compat_props, pc_compat_4_0, pc_compat_4_0_len);
> +    /* Compat props are applied by the 4.0.1 machine */
>  }
>  
>  DEFINE_Q35_MACHINE(v4_0, "pc-q35-4.0", NULL,
> diff --git a/include/hw/boards.h b/include/hw/boards.h
> index b7362af3f1d2..eaa050a7ab50 100644
> --- a/include/hw/boards.h
> +++ b/include/hw/boards.h
> @@ -293,9 +293,6 @@ struct MachineState {
>      } \
>      type_init(machine_initfn##_register_types)
>  
> -extern GlobalProperty hw_compat_4_0_1[];
> -extern const size_t hw_compat_4_0_1_len;
> -
>  extern GlobalProperty hw_compat_4_0[];
>  extern const size_t hw_compat_4_0_len;
>  
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index a7d0b8716604..c54cc54a4799 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -293,9 +293,6 @@ int e820_add_entry(uint64_t, uint64_t, uint32_t);
>  int e820_get_num_entries(void);
>  bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *);
>  
> -extern GlobalProperty pc_compat_4_0_1[];
> -extern const size_t pc_compat_4_0_1_len;
> -
>  extern GlobalProperty pc_compat_4_0[];
>  extern const size_t pc_compat_4_0_len;
>