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[PATCH v6 19/30] qemu/target-info: Add target_base_arch()

Philippe Mathieu-Daudé posted 30 patches 3 weeks, 3 days ago
Maintainers: Pierrick Bouvier <pierrick.bouvier@linaro.org>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, "Cédric Le Goater" <clg@kaod.org>, Peter Maydell <peter.maydell@linaro.org>, Steven Lee <steven_lee@aspeedtech.com>, Troy Lee <leetroy@gmail.com>, Jamin Lin <jamin_lin@aspeedtech.com>, Andrew Jeffery <andrew@codeconstruct.com.au>, Joel Stanley <joel@jms.id.au>, Samuel Tardieu <sam@rfc1149.net>, Beniamino Galvani <b.galvani@gmail.com>, Strahinja Jankovic <strahinja.p.jankovic@gmail.com>, Antony Pavlov <antonynpavlov@gmail.com>, Igor Mitsyanko <i.mitsyanko@gmail.com>, Rob Herring <robh@kernel.org>, Jean-Christophe Dubois <jcd@tribudubois.net>, Bernhard Beschow <shentey@gmail.com>, Andrey Smirnov <andrew.smirnov@gmail.com>, Subbaraya Sundeep <sundeep.lkml@gmail.com>, Jan Kiszka <jan.kiszka@web.de>, Alistair Francis <alistair@alistair23.me>, Tyrone Ting <kfting@nuvoton.com>, Hao Wu <wuhaotsh@google.com>, Felipe Balbi <balbi@kernel.org>, Niek Linnenbank <nieklinnenbank@gmail.com>, Radoslaw Biernacki <rad@semihalf.com>, Leif Lindholm <leif.lindholm@oss.qualcomm.com>, Alexandre Iooss <erdnaxe@crans.org>, "Michael S. Tsirkin" <mst@redhat.com>, Igor Mammedov <imammedo@redhat.com>, Ani Sinha <anisinha@redhat.com>, Shannon Zhao <shannon.zhaosl@gmail.com>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>, Eduardo Habkost <eduardo@habkost.net>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Yanan Wang <wangyanan55@huawei.com>, Zhao Liu <zhao1.liu@intel.com>, Paolo Bonzini <pbonzini@redhat.com>, "Marc-André Lureau" <marcandre.lureau@redhat.com>, "Daniel P. Berrangé" <berrange@redhat.com>
There is a newer version of this series
[PATCH v6 19/30] qemu/target-info: Add target_base_arch()
Posted by Philippe Mathieu-Daudé 3 weeks, 3 days ago 
When multiple QEMU targets are variants (word size, endianness)
of the same base architecture, target_base_arch() returns this
base. For example, for the Aarch64 target it will return
SYS_EMU_TARGET_ARM as common base.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 include/qemu/target-info-impl.h |  2 ++
 include/qemu/target-info-qapi.h |  7 +++++++
 target-info-stub.c              |  1 +
 target-info.c                   | 10 ++++++++++
 4 files changed, 20 insertions(+)

diff --git a/include/qemu/target-info-impl.h b/include/qemu/target-info-impl.h
index e446585bf53..2c171f8359b 100644
--- a/include/qemu/target-info-impl.h
+++ b/include/qemu/target-info-impl.h
@@ -17,6 +17,8 @@ typedef struct TargetInfo {
     const char *target_name;
     /* related to TARGET_ARCH definition */
     SysEmuTarget target_arch;
+    /* related to TARGET_BASE_ARCH definition (target/${base_arch}/ path) */
+    SysEmuTarget target_base_arch;
     /* runtime equivalent of TARGET_LONG_BITS definition */
     unsigned long_bits;
     /* runtime equivalent of CPU_RESOLVING_TYPE definition */
diff --git a/include/qemu/target-info-qapi.h b/include/qemu/target-info-qapi.h
index d5ce0523238..65ed4ca8eea 100644
--- a/include/qemu/target-info-qapi.h
+++ b/include/qemu/target-info-qapi.h
@@ -19,6 +19,13 @@
  */
 SysEmuTarget target_arch(void);
 
+/**
+ * target_base_arch:
+ *
+ * Returns: QAPI SysEmuTarget enum (i.e. SYS_EMU_TARGET_I386).
+ */
+SysEmuTarget target_base_arch(void);
+
 /**
  * target_endian_mode:
  *
diff --git a/target-info-stub.c b/target-info-stub.c
index d96d8249c1d..d2cfca1b4c2 100644
--- a/target-info-stub.c
+++ b/target-info-stub.c
@@ -19,6 +19,7 @@ QEMU_BUILD_BUG_ON(offsetof(ArchCPU, env) != sizeof(CPUState));
 static const TargetInfo target_info_stub = {
     .target_name = TARGET_NAME,
     .target_arch = SYS_EMU_TARGET__MAX,
+    .target_base_arch = SYS_EMU_TARGET__MAX,
     .long_bits = TARGET_LONG_BITS,
     .cpu_type = CPU_RESOLVING_TYPE,
     .machine_typename = TYPE_MACHINE,
diff --git a/target-info.c b/target-info.c
index e567cb4c40a..332198e40a2 100644
--- a/target-info.c
+++ b/target-info.c
@@ -33,6 +33,16 @@ SysEmuTarget target_arch(void)
     return arch;
 }
 
+SysEmuTarget target_base_arch(void)
+{
+    SysEmuTarget base_arch = target_info()->target_base_arch;
+
+    if (base_arch == SYS_EMU_TARGET__MAX) {
+        base_arch = target_arch();
+    }
+    return base_arch;
+}
+
 const char *target_cpu_type(void)
 {
     return target_info()->cpu_type;
-- 
2.51.0
Re: [PATCH v6 19/30] qemu/target-info: Add target_base_arch()
Posted by Pierrick Bouvier 3 weeks, 3 days ago 
On 2025-10-20 15:14, Philippe Mathieu-Daudé wrote:
> When multiple QEMU targets are variants (word size, endianness)
> of the same base architecture, target_base_arch() returns this
> base. For example, for the Aarch64 target it will return
> SYS_EMU_TARGET_ARM as common base.
>

I'm not sure that reusing semantic on a subset of this enum is the best 
idea, so many things can go wrong.

More widely, I don't know where we would need to access this, versus 
specific functions like target_base_arm().
If a code needs to check various base archs target_base_*, or it can use 
a switch with all variants.

If we really want to have this target_base concept, at least it deserves 
it's own enum, separate from SYS_EMU_TARGET.

> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>   include/qemu/target-info-impl.h |  2 ++
>   include/qemu/target-info-qapi.h |  7 +++++++
>   target-info-stub.c              |  1 +
>   target-info.c                   | 10 ++++++++++
>   4 files changed, 20 insertions(+)
> 
> diff --git a/include/qemu/target-info-impl.h b/include/qemu/target-info-impl.h
> index e446585bf53..2c171f8359b 100644
> --- a/include/qemu/target-info-impl.h
> +++ b/include/qemu/target-info-impl.h
> @@ -17,6 +17,8 @@ typedef struct TargetInfo {
>       const char *target_name;
>       /* related to TARGET_ARCH definition */
>       SysEmuTarget target_arch;
> +    /* related to TARGET_BASE_ARCH definition (target/${base_arch}/ path) */
> +    SysEmuTarget target_base_arch;
>       /* runtime equivalent of TARGET_LONG_BITS definition */
>       unsigned long_bits;
>       /* runtime equivalent of CPU_RESOLVING_TYPE definition */
> diff --git a/include/qemu/target-info-qapi.h b/include/qemu/target-info-qapi.h
> index d5ce0523238..65ed4ca8eea 100644
> --- a/include/qemu/target-info-qapi.h
> +++ b/include/qemu/target-info-qapi.h
> @@ -19,6 +19,13 @@
>    */
>   SysEmuTarget target_arch(void);
>   
> +/**
> + * target_base_arch:
> + *
> + * Returns: QAPI SysEmuTarget enum (i.e. SYS_EMU_TARGET_I386).
> + */
> +SysEmuTarget target_base_arch(void);
> +
>   /**
>    * target_endian_mode:
>    *
> diff --git a/target-info-stub.c b/target-info-stub.c
> index d96d8249c1d..d2cfca1b4c2 100644
> --- a/target-info-stub.c
> +++ b/target-info-stub.c
> @@ -19,6 +19,7 @@ QEMU_BUILD_BUG_ON(offsetof(ArchCPU, env) != sizeof(CPUState));
>   static const TargetInfo target_info_stub = {
>       .target_name = TARGET_NAME,
>       .target_arch = SYS_EMU_TARGET__MAX,
> +    .target_base_arch = SYS_EMU_TARGET__MAX,

And nothing can enforce base and arch match by design, which is a 
problem IMHO.

>       .long_bits = TARGET_LONG_BITS,
>       .cpu_type = CPU_RESOLVING_TYPE,
>       .machine_typename = TYPE_MACHINE,
> diff --git a/target-info.c b/target-info.c
> index e567cb4c40a..332198e40a2 100644
> --- a/target-info.c
> +++ b/target-info.c
> @@ -33,6 +33,16 @@ SysEmuTarget target_arch(void)
>       return arch;
>   }
>   
> +SysEmuTarget target_base_arch(void)
> +{
> +    SysEmuTarget base_arch = target_info()->target_base_arch;
> +
> +    if (base_arch == SYS_EMU_TARGET__MAX) {
> +        base_arch = target_arch();
> +    }
> +    return base_arch;

More confusing, we can eventually return a non base arch if base arch 
was not correctly set above.

> +}
> +
>   const char *target_cpu_type(void)
>   {
>       return target_info()->cpu_type;
Re: [PATCH v6 19/30] qemu/target-info: Add target_base_arch()
Posted by Philippe Mathieu-Daudé 3 weeks, 3 days ago 
On 21/10/25 01:15, Pierrick Bouvier wrote:
> On 2025-10-20 15:14, Philippe Mathieu-Daudé wrote:
>> When multiple QEMU targets are variants (word size, endianness)
>> of the same base architecture, target_base_arch() returns this
>> base. For example, for the Aarch64 target it will return
>> SYS_EMU_TARGET_ARM as common base.
>>
> 
> I'm not sure that reusing semantic on a subset of this enum is the best 
> idea, so many things can go wrong.
> 
> More widely, I don't know where we would need to access this, versus 
> specific functions like target_base_arm().
> If a code needs to check various base archs target_base_*, or it can use 
> a switch with all variants.

Yeah, good point. I'll just drop this single patch.

> 
> If we really want to have this target_base concept, at least it deserves 
> it's own enum, separate from SYS_EMU_TARGET.
> 
>> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
>> ---
>>   include/qemu/target-info-impl.h |  2 ++
>>   include/qemu/target-info-qapi.h |  7 +++++++
>>   target-info-stub.c              |  1 +
>>   target-info.c                   | 10 ++++++++++
>>   4 files changed, 20 insertions(+)
>>
>> diff --git a/include/qemu/target-info-impl.h b/include/qemu/target- 
>> info-impl.h
>> index e446585bf53..2c171f8359b 100644
>> --- a/include/qemu/target-info-impl.h
>> +++ b/include/qemu/target-info-impl.h
>> @@ -17,6 +17,8 @@ typedef struct TargetInfo {
>>       const char *target_name;
>>       /* related to TARGET_ARCH definition */
>>       SysEmuTarget target_arch;
>> +    /* related to TARGET_BASE_ARCH definition (target/${base_arch}/ 
>> path) */
>> +    SysEmuTarget target_base_arch;
>>       /* runtime equivalent of TARGET_LONG_BITS definition */
>>       unsigned long_bits;
>>       /* runtime equivalent of CPU_RESOLVING_TYPE definition */
>> diff --git a/include/qemu/target-info-qapi.h b/include/qemu/target- 
>> info-qapi.h
>> index d5ce0523238..65ed4ca8eea 100644
>> --- a/include/qemu/target-info-qapi.h
>> +++ b/include/qemu/target-info-qapi.h
>> @@ -19,6 +19,13 @@
>>    */
>>   SysEmuTarget target_arch(void);
>> +/**
>> + * target_base_arch:
>> + *
>> + * Returns: QAPI SysEmuTarget enum (i.e. SYS_EMU_TARGET_I386).
>> + */
>> +SysEmuTarget target_base_arch(void);
>> +
>>   /**
>>    * target_endian_mode:
>>    *
>> diff --git a/target-info-stub.c b/target-info-stub.c
>> index d96d8249c1d..d2cfca1b4c2 100644
>> --- a/target-info-stub.c
>> +++ b/target-info-stub.c
>> @@ -19,6 +19,7 @@ QEMU_BUILD_BUG_ON(offsetof(ArchCPU, env) != 
>> sizeof(CPUState));
>>   static const TargetInfo target_info_stub = {
>>       .target_name = TARGET_NAME,
>>       .target_arch = SYS_EMU_TARGET__MAX,
>> +    .target_base_arch = SYS_EMU_TARGET__MAX,
> 
> And nothing can enforce base and arch match by design, which is a 
> problem IMHO.
> 
>>       .long_bits = TARGET_LONG_BITS,
>>       .cpu_type = CPU_RESOLVING_TYPE,
>>       .machine_typename = TYPE_MACHINE,
>> diff --git a/target-info.c b/target-info.c
>> index e567cb4c40a..332198e40a2 100644
>> --- a/target-info.c
>> +++ b/target-info.c
>> @@ -33,6 +33,16 @@ SysEmuTarget target_arch(void)
>>       return arch;
>>   }
>> +SysEmuTarget target_base_arch(void)
>> +{
>> +    SysEmuTarget base_arch = target_info()->target_base_arch;
>> +
>> +    if (base_arch == SYS_EMU_TARGET__MAX) {
>> +        base_arch = target_arch();
>> +    }
>> +    return base_arch;
> 
> More confusing, we can eventually return a non base arch if base arch 
> was not correctly set above.
> 
>> +}
>> +
>>   const char *target_cpu_type(void)
>>   {
>>       return target_info()->cpu_type;

Patchew 2.1-devel-b67e4c2

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