[PATCH 0/2] rust: Kconfig: factor out Rust vs C impl choice

[PATCH 0/2] rust: Kconfig: factor out Rust vs C impl choice

[Peter Maydell]

This patchset fixes a compilation failure if CONFIG_VMAPPLE is
enabled in a Rust build, which happens because hw/vmapple/Kconfig
didn't have the "pick the Rust PL011 if Rust is enabled" logic in it.
Rather than just adding that to yet another PL011-using board
model, this patchset refactors how we handle devices which have
both a Rust and C implementation in Kconfig:
 * CONFIG_PL011 is "do we have/want a PL011 of some kind"
 * CONFIG_PL011_C is the C impl
 * CONFIG_X_PL011_RUST is the rust impl
 * selecting CONFIG_PL011 pulls in one impl or the other
   depending on whether the build has Rust enabled or not

For the PL011, this lets us drop a lot of duplicate logic
in Kconfig files for boards; for HPET this simplifies
places in code that have ifdefs for "do we have an HPET?".

NB: I think this should be OK but haven't been able to do
complete testing because currently in head-of-git
"make check-functional" doesn't pass for arm with Rust
enabled due to a different issue.

thanks
-- PMM

Peter Maydell (2):
  rust: Kconfig: Factor out whether PL011 is Rust or C
  rust: Kconfig: Factor out whether HPET is Rust or C

 configs/devices/i386-softmmu/default.mak |  1 -
 hw/i386/fw_cfg.c                         |  2 +-
 hw/i386/pc.c                             |  2 +-
 hw/arm/Kconfig                           | 30 ++++++++----------------
 hw/char/Kconfig                          |  6 +++++
 hw/char/meson.build                      |  2 +-
 hw/timer/Kconfig                         |  8 ++++++-
 hw/timer/meson.build                     |  2 +-
 rust/hw/timer/Kconfig                    |  1 -
 tests/qtest/meson.build                  |  3 +--
 10 files changed, 28 insertions(+), 29 deletions(-)

-- 
2.43.0

[PATCH 1/2] rust: Kconfig: Factor out whether PL011 is Rust or C

[Peter Maydell]

Currently every board that uses the PL011 duplicates the logic that
selects the Rust implementation if Rust was enabled and the C
implementation if it does not.  Factor this out into a separate
Kconfig stanza, so that boards can go back to simply doing "select
PL011" and get whichever implementation is correct for the build.

This fixes a compilation failure if CONFIG_VMAPPLE is enabled
in a Rust build, because hw/vmapple/Kconfig didn't have the
"pick the Rust PL011 if Rust is enabled" logic in it.

Fixes: 59f4d65584bd33 ("hw/vmapple/vmapple: Add vmapple machine type")
Reported-by: Tanish Desai <tanishdesai37@gmail.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/arm/Kconfig      | 30 ++++++++++--------------------
 hw/char/Kconfig     |  6 ++++++
 hw/char/meson.build |  2 +-
 3 files changed, 17 insertions(+), 21 deletions(-)

diff --git a/hw/arm/Kconfig b/hw/arm/Kconfig
index 15200a2d7e7..a55b44d7bde 100644
--- a/hw/arm/Kconfig
+++ b/hw/arm/Kconfig
@@ -21,8 +21,7 @@ config ARM_VIRT
     select PCI_EXPRESS
     select PCI_EXPRESS_GENERIC_BRIDGE
     select PFLASH_CFI01
-    select PL011 if !HAVE_RUST # UART
-    select X_PL011_RUST if HAVE_RUST # UART
+    select PL011 # UART
     select PL031 # RTC
     select PL061 # GPIO
     select GPIO_PWR
@@ -75,8 +74,7 @@ config HIGHBANK
     select AHCI_SYSBUS
     select ARM_TIMER # sp804
     select ARM_V7M
-    select PL011 if !HAVE_RUST # UART
-    select X_PL011_RUST if HAVE_RUST # UART
+    select PL011 # UART
     select PL022 # SPI
     select PL031 # RTC
     select PL061 # GPIO
@@ -89,8 +87,7 @@ config INTEGRATOR
     depends on TCG && ARM
     select ARM_TIMER
     select INTEGRATOR_DEBUG
-    select PL011 if !HAVE_RUST # UART
-    select X_PL011_RUST if HAVE_RUST # UART
+    select PL011 # UART
     select PL031 # RTC
     select PL041 # audio
     select PL050 # keyboard/mouse
@@ -108,8 +105,7 @@ config MUSCA
     default y
     depends on TCG && ARM
     select ARMSSE
-    select PL011 if !HAVE_RUST # UART
-    select X_PL011_RUST if HAVE_RUST # UART
+    select PL011 # UART
     select PL031
     select SPLIT_IRQ
     select UNIMP
@@ -173,8 +169,7 @@ config REALVIEW
     select WM8750 # audio codec
     select LSI_SCSI_PCI
     select PCI
-    select PL011 if !HAVE_RUST # UART
-    select X_PL011_RUST if HAVE_RUST # UART
+    select PL011 # UART
     select PL031  # RTC
     select PL041  # audio codec
     select PL050  # keyboard/mouse
@@ -199,8 +194,7 @@ config SBSA_REF
     select PCI_EXPRESS
     select PCI_EXPRESS_GENERIC_BRIDGE
     select PFLASH_CFI01
-    select PL011 if !HAVE_RUST # UART
-    select X_PL011_RUST if HAVE_RUST # UART
+    select PL011 # UART
     select PL031 # RTC
     select PL061 # GPIO
     select USB_XHCI_SYSBUS
@@ -224,8 +218,7 @@ config STELLARIS
     select ARM_V7M
     select CMSDK_APB_WATCHDOG
     select I2C
-    select PL011 if !HAVE_RUST # UART
-    select X_PL011_RUST if HAVE_RUST # UART
+    select PL011 # UART
     select PL022 # SPI
     select PL061 # GPIO
     select SSD0303 # OLED display
@@ -285,8 +278,7 @@ config VEXPRESS
     select ARM_TIMER # sp804
     select LAN9118
     select PFLASH_CFI01
-    select PL011 if !HAVE_RUST # UART
-    select X_PL011_RUST if HAVE_RUST # UART
+    select PL011 # UART
     select PL041 # audio codec
     select PL181  # display
     select REALVIEW
@@ -371,8 +363,7 @@ config RASPI
     default y
     depends on TCG && ARM
     select FRAMEBUFFER
-    select PL011 if !HAVE_RUST # UART
-    select X_PL011_RUST if HAVE_RUST # UART
+    select PL011 # UART
     select SDHCI
     select USB_DWC2
     select BCM2835_SPI
@@ -448,8 +439,7 @@ config XLNX_VERSAL
     select ARM_GIC
     select CPU_CLUSTER
     select DEVICE_TREE
-    select PL011 if !HAVE_RUST # UART
-    select X_PL011_RUST if HAVE_RUST # UART
+    select PL011 # UART
     select CADENCE
     select VIRTIO_MMIO
     select UNIMP
diff --git a/hw/char/Kconfig b/hw/char/Kconfig
index 3f702565e67..9d517f3e287 100644
--- a/hw/char/Kconfig
+++ b/hw/char/Kconfig
@@ -11,6 +11,12 @@ config PARALLEL
 
 config PL011
     bool
+    # The PL011 has both a Rust and a C implementation
+    select PL011_C if !HAVE_RUST
+    select X_PL011_RUST if HAVE_RUST
+
+config PL011_C
+    bool
 
 config SERIAL
     bool
diff --git a/hw/char/meson.build b/hw/char/meson.build
index 86ee808cae7..4e439da8b9e 100644
--- a/hw/char/meson.build
+++ b/hw/char/meson.build
@@ -9,7 +9,7 @@ system_ss.add(when: 'CONFIG_ISA_BUS', if_true: files('parallel-isa.c'))
 system_ss.add(when: 'CONFIG_ISA_DEBUG', if_true: files('debugcon.c'))
 system_ss.add(when: 'CONFIG_NRF51_SOC', if_true: files('nrf51_uart.c'))
 system_ss.add(when: 'CONFIG_PARALLEL', if_true: files('parallel.c'))
-system_ss.add(when: 'CONFIG_PL011', if_true: files('pl011.c'))
+system_ss.add(when: 'CONFIG_PL011_C', if_true: files('pl011.c'))
 system_ss.add(when: 'CONFIG_SCLPCONSOLE', if_true: files('sclpconsole.c', 'sclpconsole-lm.c'))
 system_ss.add(when: 'CONFIG_SERIAL', if_true: files('serial.c'))
 system_ss.add(when: 'CONFIG_SERIAL_ISA', if_true: files('serial-isa.c'))
-- 
2.43.0

[PATCH 2/2] rust: Kconfig: Factor out whether HPET is Rust or C

[Peter Maydell]

Currently we require everywhere that wants to know if there
is an HPET device to check for "CONFIG_HPET || CONFIG_X_HPET_RUST".
Factor out whether the HPET device is Rust or C into a separate
Kconfig stanza, so that CONFIG_HPET means "there is an HPET",
and whether this has pulled in CONFIG_X_HPET_RUST or CONFIG_HPET_C
is something the rest of QEMU can ignore.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 configs/devices/i386-softmmu/default.mak | 1 -
 hw/i386/fw_cfg.c                         | 2 +-
 hw/i386/pc.c                             | 2 +-
 hw/timer/Kconfig                         | 8 +++++++-
 hw/timer/meson.build                     | 2 +-
 rust/hw/timer/Kconfig                    | 1 -
 tests/qtest/meson.build                  | 3 +--
 7 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/configs/devices/i386-softmmu/default.mak b/configs/devices/i386-softmmu/default.mak
index 9ef343cace0..4faf2f0315e 100644
--- a/configs/devices/i386-softmmu/default.mak
+++ b/configs/devices/i386-softmmu/default.mak
@@ -6,7 +6,6 @@
 #CONFIG_APPLESMC=n
 #CONFIG_FDC=n
 #CONFIG_HPET=n
-#CONFIG_X_HPET_RUST=n
 #CONFIG_HYPERV=n
 #CONFIG_ISA_DEBUG=n
 #CONFIG_ISA_IPMI_BT=n
diff --git a/hw/i386/fw_cfg.c b/hw/i386/fw_cfg.c
index a7f1b60b98c..5c0bcd5f8a9 100644
--- a/hw/i386/fw_cfg.c
+++ b/hw/i386/fw_cfg.c
@@ -26,7 +26,7 @@
 #include CONFIG_DEVICES
 #include "target/i386/cpu.h"
 
-#if !defined(CONFIG_HPET) && !defined(CONFIG_X_HPET_RUST)
+#if !defined(CONFIG_HPET)
 struct hpet_fw_config hpet_fw_cfg = {.count = UINT8_MAX};
 #endif
 
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 63a96cd23f8..01d0581f62a 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1704,7 +1704,7 @@ static void pc_machine_initfn(Object *obj)
     pcms->sata_enabled = true;
     pcms->i8042_enabled = true;
     pcms->max_fw_size = 8 * MiB;
-#if defined(CONFIG_HPET) || defined(CONFIG_X_HPET_RUST)
+#if defined(CONFIG_HPET)
     pcms->hpet_enabled = true;
 #endif
     pcms->fd_bootchk = true;
diff --git a/hw/timer/Kconfig b/hw/timer/Kconfig
index 9ac00845340..b3d823ce2c3 100644
--- a/hw/timer/Kconfig
+++ b/hw/timer/Kconfig
@@ -11,7 +11,13 @@ config A9_GTIMER
 
 config HPET
     bool
-    default y if PC && !HAVE_RUST
+    default y if PC
+    # The HPET has both a Rust and a C implementation
+    select HPET_C if !HAVE_RUST
+    select X_HPET_RUST if HAVE_RUST
+
+config HPET_C
+    bool
 
 config I8254
     bool
diff --git a/hw/timer/meson.build b/hw/timer/meson.build
index f5f9eed2d0a..178321c029c 100644
--- a/hw/timer/meson.build
+++ b/hw/timer/meson.build
@@ -13,7 +13,7 @@ system_ss.add(when: 'CONFIG_DIGIC', if_true: files('digic-timer.c'))
 system_ss.add(when: 'CONFIG_EXYNOS4', if_true: files('exynos4210_mct.c'))
 system_ss.add(when: 'CONFIG_EXYNOS4', if_true: files('exynos4210_pwm.c'))
 system_ss.add(when: 'CONFIG_GRLIB', if_true: files('grlib_gptimer.c'))
-system_ss.add(when: 'CONFIG_HPET', if_true: files('hpet.c'))
+system_ss.add(when: 'CONFIG_HPET_C', if_true: files('hpet.c'))
 system_ss.add(when: 'CONFIG_I8254', if_true: files('i8254_common.c', 'i8254.c'))
 system_ss.add(when: 'CONFIG_IMX', if_true: files('imx_epit.c'))
 system_ss.add(when: 'CONFIG_IMX', if_true: files('imx_gpt.c'))
diff --git a/rust/hw/timer/Kconfig b/rust/hw/timer/Kconfig
index 42e421317a5..afd98033503 100644
--- a/rust/hw/timer/Kconfig
+++ b/rust/hw/timer/Kconfig
@@ -1,3 +1,2 @@
 config X_HPET_RUST
     bool
-    default y if PC && HAVE_RUST
diff --git a/tests/qtest/meson.build b/tests/qtest/meson.build
index 5a8c1f102c2..3136d15e0f8 100644
--- a/tests/qtest/meson.build
+++ b/tests/qtest/meson.build
@@ -103,8 +103,7 @@ qtests_i386 = \
    config_all_devices.has_key('CONFIG_VIRTIO_PCI') and                                      \
    slirp.found() ? ['virtio-net-failover'] : []) +                                          \
   (unpack_edk2_blobs and                                                                    \
-   (config_all_devices.has_key('CONFIG_HPET') or                                            \
-    config_all_devices.has_key('CONFIG_X_HPET_RUST')) and                                   \
+   config_all_devices.has_key('CONFIG_HPET') and                                            \
    config_all_devices.has_key('CONFIG_PARALLEL') ? ['bios-tables-test'] : []) +             \
   qtests_pci +                                                                              \
   qtests_cxl +                                                                              \
-- 
2.43.0

Re: [PATCH 1/2] rust: Kconfig: Factor out whether PL011 is Rust or C

[Philippe Mathieu-Daudé]

On 19/3/25 20:31, Peter Maydell wrote:
> Currently every board that uses the PL011 duplicates the logic that
> selects the Rust implementation if Rust was enabled and the C
> implementation if it does not.  Factor this out into a separate
> Kconfig stanza, so that boards can go back to simply doing "select
> PL011" and get whichever implementation is correct for the build.
> 
> This fixes a compilation failure if CONFIG_VMAPPLE is enabled
> in a Rust build, because hw/vmapple/Kconfig didn't have the
> "pick the Rust PL011 if Rust is enabled" logic in it.
> 
> Fixes: 59f4d65584bd33 ("hw/vmapple/vmapple: Add vmapple machine type")
> Reported-by: Tanish Desai <tanishdesai37@gmail.com>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>   hw/arm/Kconfig      | 30 ++++++++++--------------------
>   hw/char/Kconfig     |  6 ++++++
>   hw/char/meson.build |  2 +-
>   3 files changed, 17 insertions(+), 21 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>