feat(libkernel): implement sceKernelGetAllowedSdkVersionOnSystem

AI-assisted: yes

core/libs/prx/libkernel/System/src/SoftwareVersion.cpp

@@ -19,6 +19,7 @@ namespace {
 
 constexpr std::uint32_t SystemSoftwareVersion = 0x01000000;
 constexpr char SystemSoftwareVersionString[] = "01.000.000";
+constexpr std::uint32_t SdkPatchMask = 0xfff;
 
 }
 
@@ -33,4 +34,10 @@ int APS5_VABI sceKernelGetProsperoSystemSwVersion_nid_postfix(SceKernelProsperoS
     return 0;
 }
 
+int APS5_VABI sceKernelGetAllowedSdkVersionOnSystem_nid_postfix(std::uint32_t* version) {
+    if (version == nullptr) return SCE_KERNEL_ERROR_EINVAL;
+    *version = SystemSoftwareVersion | SdkPatchMask;
+    return 0;
+}
+
 }

core/libs/tests/GuestSoftwareVersion.cpp

@@ -18,6 +18,7 @@ static_assert(sizeof(SceKernelProsperoSystemSwVersion) == 0x28);
 extern "C" {
 int* APS5_VABI __error_nid_postfix();
 int APS5_VABI sceKernelGetProsperoSystemSwVersion_nid_postfix(SceKernelProsperoSystemSwVersion*);
+int APS5_VABI sceKernelGetAllowedSdkVersionOnSystem_nid_postfix(std::uint32_t*);
 }
 
 static void Require(bool value) { if (!value) std::abort(); }
@@ -44,7 +45,20 @@ static void CheckProsperoSystemSwVersion() {
     Require(*__error_nid_postfix() == 13);
 }
 
+static void CheckAllowedSdkVersionOnSystem() {
+    *__error_nid_postfix() = 13;
+    Require(sceKernelGetAllowedSdkVersionOnSystem_nid_postfix(nullptr) == SCE_KERNEL_ERROR_EINVAL);
+    std::uint32_t allowed = 0xaaaaaaaa;
+    Require(sceKernelGetAllowedSdkVersionOnSystem_nid_postfix(&allowed) == 0);
+    SceKernelProsperoSystemSwVersion system{};
+    system.size = sizeof(system);
+    Require(sceKernelGetProsperoSystemSwVersion_nid_postfix(&system) == 0);
+    Require(allowed == (system.version | 0xfff) && allowed >> 16 == system.version >> 16);
+    Require(*__error_nid_postfix() == 13);
+}
+
 int main() {
     CheckProsperoSystemSwVersion();
+    CheckAllowedSdkVersionOnSystem();
     return 0;
 }

docs/dev/TechnicalDebt.md

@@ -49,6 +49,7 @@ Throughout the project, every function at every stage either **does exactly what
 - [sceNpGetSandboxInfo](../../core/libs/prx/libSceNpManager/Export.cpp) (libSceNpManager, NID `ZVZ++68nNI8`) - the name hashes to the imported NID (found with nidhunt, confirmed with `tools/nid_names.py`). STAR WARS: Galactic Racer (PPSA28416) imports it; its OnlineSubsystemPS5 calls it with one pointer to a 0x50-byte stack buffer and reads the buffer as a string (discussions/3086). The returned string, the exact parameter struct and console errors are unknown, so every call throws without reading or writing caller memory. A working implementation belongs with that title's bring-up.
 - [sceVideoOutGetOutputStatusWithVrr](../../core/libs/prx/libSceVideoOut/Unimplemented.cpp) (libSceVideoOut, NID `gWT7X8H0bYs`) - the name hashes to the imported NID. PPSA26344 version 02.002.000 passes a VideoOut handle and an output pointer at three call sites. It compares a 32-bit value at byte 4 with 2, tests bit 0x10 at byte 16, and, when set, compares low 16-bit values at bytes 48, 50 and 52 with 48, 60 and 120. The full output layout, size, field meanings and console errors are unknown. Every call throws without reading or writing caller memory.
 - [sceKernelGetProsperoSystemSwVersion](../../core/libs/prx/libkernel/System/src/SoftwareVersion.cpp) (libkernel) reports system software version `0x01000000` ("01.000.000"); the console's firmware version is not modeled. The 0x28-byte block (a 64-bit size at 0, the version string at 8 and the packed version at 0x24) follows [SharpProspero](https://github.com/SvenGDK/SharpProspero/blob/main/src/SharpProspero/Interop/Kernel/KernelSystem.cs), which Prospero Multi Tools (PPSA99110) and Prospero Explorer (PPSA99109) are built with and which sets the size to 40, and the same fields in [etaHEN](https://github.com/etaHEN/etaHEN/blob/main/Source%20Code/daemon/include/ipc.hpp) and [shsrv](https://github.com/ps5-payload-dev/shsrv/blob/master/sh.c). A size other than 0x28 returns `SCE_KERNEL_ERROR_EINVAL` without writing; whether the console checks the size is unverified, since etaHEN and shsrv declare a 0x30-byte block and do not set it
+- [sceKernelGetAllowedSdkVersionOnSystem](../../core/libs/prx/libkernel/System/src/SoftwareVersion.cpp) (libkernel) reports the system software version with the 12 patch bits set, `0x01000fff`, as [shadPS4](https://github.com/shadps4-emu/shadPS4/blob/98fd0689/src/core/libraries/kernel/kernel.cpp) does on the PS4 and as [SharpProspero](https://github.com/SvenGDK/SharpProspero/blob/main/src/SharpProspero/Interop/Kernel/KernelSystem.cs) describes it, which Prospero Explorer (PPSA99109) reads it through; a null pointer returns `SCE_KERNEL_ERROR_EINVAL`. The console's value and its errors are unverified
 - [getuid, geteuid, getgid, getegid and issetugid](../../core/libs/prx/libkernel/System/src/Process.cpp) (libkernel) report the root identity (0) and a process that never changed credentials (`issetugid` 0), as a jailbroken process has; the host user and group are not exposed to the guest. The values a title sees on a console are unverified
 - [sceKernelGetAppInfo](../../core/libs/prx/libkernel/System/src/Process.cpp) (libkernel) - only `app_id` and the title ID (offset 0x10, up to 9 characters plus a terminator) are written; callers declare the structure with different sizes, so the rest is left alone. `app_id` is 1, the running title's id in libSceSystemService, which is a guess, not something measured. The error codes follow shadPS4: `EPERM` for another process, and 0 without writing anything for a null pointer.
 - [sceFontSetScriptLanguage, sceFontGetScriptLanguage, sceFontSetTypographicDesign, sceFontGetTypographicDesign](../../core/libs/prx/libSceFont/src/Style.cpp) (libSceFont) - signatures follow [SharpProspero](https://github.com/SvenGDK/SharpProspero/blob/main/src/SharpProspero/Interop/Font/SceFont.cs), not confirmed for the PS5. The handle keeps the language set for each script and the feature set for each typographic design and returns them, with 0 for one never set; the console default and its valid ranges are unknown, so any value is accepted. Neither setting changes shaping or rendering yet