Current code uses CPUHPPAState::@kernel_entry to hold either:
 - kernel entry virtual address
 - firmware interactive mode
and CPUHPPAState::@cmdline_or_bootorder to either:
 - kernel &cmdline physical address
 - firmware boot order

Besides, these variables don't belong to CPUHPPAState, they
depend on how the machine is started, and only apply to the
first CPU.

The MachineReset handler initialize some registers of the
first CPU. Hold these register reset values in the MachineState,
initializing them once in machine_HP_common_init_tail().

Start by addressing the kernel entry and firmware interactive
mode values, stored in $GP25.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 target/hppa/cpu.h |  1 -
 hw/hppa/machine.c | 28 ++++++++++++++++------------
 2 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/target/hppa/cpu.h b/target/hppa/cpu.h
index e14f238827b..f54634db7f1 100644
--- a/target/hppa/cpu.h
+++ b/target/hppa/cpu.h
@@ -272,7 +272,6 @@ typedef struct CPUArchState {
 
     bool is_pa20;
 
-    target_ulong kernel_entry; /* Linux kernel was loaded here */
     target_ulong cmdline_or_bootorder;
     target_ulong initrd_base, initrd_end;
 } CPUHPPAState;
diff --git a/hw/hppa/machine.c b/hw/hppa/machine.c
index cddca69b938..7066f6d575c 100644
--- a/hw/hppa/machine.c
+++ b/hw/hppa/machine.c
@@ -41,6 +41,10 @@ OBJECT_DECLARE_SIMPLE_TYPE(HppaMachineState, HPPA_COMMON_MACHINE)
 
 struct HppaMachineState {
     MachineState parent_obj;
+
+    struct {
+        uint64_t gr25;
+    } boot_info;
 };
 
 #define MIN_SEABIOS_HPPA_VERSION 12 /* require at least this fw version */
@@ -353,10 +357,10 @@ static void machine_HP_common_init_tail(MachineState *machine, PCIBus *pci_bus,
 {
     const char *kernel_filename = machine->kernel_filename;
     MachineClass *mc = MACHINE_GET_CLASS(machine);
+    HppaMachineState *hms = HPPA_COMMON_MACHINE(machine);
     DeviceState *dev;
     PCIDevice *pci_dev;
     long size;
-    uint64_t kernel_entry = 0;
     MemoryRegion *addr_space = get_system_memory();
     MemoryRegion *rom_region;
     SysBusDevice *s;
@@ -468,7 +472,7 @@ static void machine_HP_common_init_tail(MachineState *machine, PCIBus *pci_bus,
     if (kernel_filename) {
         const char *kernel_cmdline = machine->kernel_cmdline;
         const char *initrd_filename = machine->initrd_filename;
-        uint64_t kernel_low, kernel_high;
+        uint64_t kernel_entry, kernel_low, kernel_high;
 
         size = load_elf(kernel_filename, NULL, linux_kernel_virt_to_phys,
                         NULL, &kernel_entry, &kernel_low, &kernel_high, NULL,
@@ -484,6 +488,8 @@ static void machine_HP_common_init_tail(MachineState *machine, PCIBus *pci_bus,
                       "-0x%08" PRIx64 ", entry at 0x%08" PRIx64
                       ", size %" PRIu64 " kB\n",
                       kernel_low, kernel_high, kernel_entry, size / KiB);
+        /* Keep initial kernel_entry for first boot */
+        hms->boot_info.gr25 = kernel_entry;
 
         if (kernel_cmdline) {
             cpu[0]->env.cmdline_or_bootorder = 0x4000;
@@ -520,19 +526,16 @@ static void machine_HP_common_init_tail(MachineState *machine, PCIBus *pci_bus,
             cpu[0]->env.initrd_base = initrd_base;
             cpu[0]->env.initrd_end  = initrd_base + initrd_size;
         }
-    }
-
-    if (!kernel_entry) {
+    } else {
         /* When booting via firmware, tell firmware if we want interactive
-         * mode (kernel_entry=1), and to boot from CD (cmdline_or_bootorder='d')
+         * mode (interactive_mode=1), and to boot from CD (cmdline_or_bootorder='d')
          * or hard disc (cmdline_or_bootorder='c').
          */
-        kernel_entry = machine->boot_config.has_menu ? machine->boot_config.menu : 0;
+        hms->boot_info.gr25 = machine->boot_config.has_menu
+                            ? machine->boot_config.menu
+                            : 0;
         cpu[0]->env.cmdline_or_bootorder = machine->boot_config.order[0];
     }
-
-    /* Keep initial kernel_entry for first boot */
-    cpu[0]->env.kernel_entry = kernel_entry;
 }
 
 /*
@@ -650,6 +653,7 @@ static void machine_HP_C3700_init(MachineState *machine)
 
 static void hppa_machine_reset(MachineState *ms, ResetType type)
 {
+    HppaMachineState *hms = HPPA_COMMON_MACHINE(ms);
     unsigned int smp_cpus = ms->smp.cpus;
     int i;
 
@@ -670,7 +674,7 @@ static void hppa_machine_reset(MachineState *ms, ResetType type)
     }
 
     cpu[0]->env.gr[26] = ms->ram_size;
-    cpu[0]->env.gr[25] = cpu[0]->env.kernel_entry;
+    cpu[0]->env.gr[25] = hms->boot_info.gr25;
     cpu[0]->env.gr[24] = cpu[0]->env.cmdline_or_bootorder;
     cpu[0]->env.gr[23] = cpu[0]->env.initrd_base;
     cpu[0]->env.gr[22] = cpu[0]->env.initrd_end;
@@ -678,7 +682,7 @@ static void hppa_machine_reset(MachineState *ms, ResetType type)
     cpu[0]->env.gr[19] = FW_CFG_IO_BASE;
 
     /* reset static fields to avoid starting Linux kernel & initrd on reboot */
-    cpu[0]->env.kernel_entry = 0;
+    memset(&hms->boot_info, 0, sizeof(hms->boot_info));
     cpu[0]->env.initrd_base = 0;
     cpu[0]->env.initrd_end = 0;
     cpu[0]->env.cmdline_or_bootorder = 'c';
-- 
2.51.0

On 10/9/25 23:18, Philippe Mathieu-Daudé wrote:
> Current code uses CPUHPPAState::@kernel_entry to hold either:
>   - kernel entry virtual address
>   - firmware interactive mode
> and CPUHPPAState::@cmdline_or_bootorder to either:
>   - kernel &cmdline physical address
>   - firmware boot order
> 
> Besides, these variables don't belong to CPUHPPAState, they
> depend on how the machine is started, and only apply to the
> first CPU.
> 
> The MachineReset handler initialize some registers of the
> first CPU. Hold these register reset values in the MachineState,
> initializing them once in machine_HP_common_init_tail().
> 
> Start by addressing the kernel entry and firmware interactive
> mode values, stored in $GP25.
> 
> Suggested-by: Richard Henderson <richard.henderson@linaro.org>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>   target/hppa/cpu.h |  1 -
>   hw/hppa/machine.c | 28 ++++++++++++++++------------
>   2 files changed, 16 insertions(+), 13 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

> -    }
> -
> -    if (!kernel_entry) {
> +    } else {
>           /* When booting via firmware, tell firmware if we want interactive
> -         * mode (kernel_entry=1), and to boot from CD (cmdline_or_bootorder='d')
> +         * mode (interactive_mode=1), and to boot from CD (cmdline_or_bootorder='d')
>            * or hard disc (cmdline_or_bootorder='c').
>            */
> -        kernel_entry = machine->boot_config.has_menu ? machine->boot_config.menu : 0;
> +        hms->boot_info.gr25 = machine->boot_config.has_menu
> +                            ? machine->boot_config.menu
> +                            : 0;

There is no interactive_mode variable, so the change to the comment isn't great.  Perhaps 
just mention gr25.

As an aside, the expression involves two booleans, so better written as

   machine->boot_config.has_menu && machine->boot_config.menu


r~