From 26cc6eb96a90fb86352e0cc06c1e7ac9025ad109 Mon Sep 17 00:00:00 2001
From: Scott Duensing <scott.duensing@gmail.com>
Date: Fri, 14 Aug 2026 18:01:21 -0500
Subject: [PATCH] Linker fixes.

---
 src/link816/link816.cpp | 42 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/src/link816/link816.cpp b/src/link816/link816.cpp
index 954e754..b399cb4 100644
--- a/src/link816/link816.cpp
+++ b/src/link816/link816.cpp
@@ -548,9 +548,16 @@ static uint32_t relocWidth(uint8_t rtype) {
 }
 
 
+unsigned long gDbgBareCalls = 0;
+unsigned long gDbgTextCalls = 0;
 static void applyReloc(std::vector<uint8_t> &buf, uint32_t off,
                        uint32_t patchAddr, uint32_t target,
                        uint8_t rtype, const std::string &symName) {
+    extern unsigned long gDbgBareCalls;
+    gDbgBareCalls++;
+    if (symName.find("gRnInPack") != std::string::npos) {
+        std::fprintf(stderr, "TRACE-BARE %s rtype=%u target=0x%X off=0x%X\n", symName.c_str(), rtype, target, off);
+    }
     int64_t pcrelDisp;
     switch (rtype) {
     case R_W65816_IMM8:
@@ -766,6 +773,12 @@ static void applyTextReloc(std::vector<uint8_t> &buf, uint32_t off,
     }
     const TextSeg &pseg = segments[patchSeg - 1];
     uint32_t targetSeg = findSegContaining(target, segments);
+    gDbgTextCalls++;
+    // TEMP TRACE (RetroNet hunt): decisions for the mirror-pack refs.
+    if (symName.find("gRnInPack") != std::string::npos) {
+        std::fprintf(stderr, "TRACE %s rtype=%u patchSeg=%u targetSeg=%u target=0x%X rec=%d\n",
+                     symName.c_str(), rtype, patchSeg, targetSeg, target, (int)gRecordSites);
+    }
     // Cross-segment FUNCTION POINTER (IMM16 &func to a function in seg2+):
     // clang forms the pointer as func's 16-bit offset + the $00BE seg1 bank,
     // which is wrong for a function in another bank.  Redirect the IMM16 to
@@ -792,6 +805,34 @@ static void applyTextReloc(std::vector<uint8_t> &buf, uint32_t off,
     // per-seg list for seg 1, since rodata is in seg 1's bank by
     // design).
     if (targetSeg == 0) {
+        // BANK-0 DATA/BSS target (inside SEG1's payload) referenced with a LONG form from an
+        // overflow segment: the baked bank byte would be the LINK-TIME bank (0), but the Loader
+        // places seg1 in an arbitrary bank - every such read/write silently hits the wrong bank
+        // (measured live on the RetroNet IIgs client: cross-TU constant-index accesses compile to
+        // LDA long and returned garbage while DBR-relative abs16 to the same symbols worked).
+        // Emit a 3-byte cINTERSEG against seg 1 so the Loader writes the true 24-bit address.
+        // ...and the SAME hole exists for 16-bit forms: seg1 is only PAGE-aligned by the real
+        // GS/OS Loader (it does not honor ALIGN=$10000), so abs16 operands and bank-byte
+        // materializations referencing seg1 data are wrong by seg1's placement offset unless the
+        // Loader patches them.  Emit 2-byte cINTERSEG records for those too; BANKSIZE=$10000
+        // guarantees seg1 never straddles a bank, so offset16+DBR stays coherent.
+        if (gRecordSites && patchSeg >= 1 && !segments.empty() &&
+            (rtype == R_W65816_IMM24 || rtype == R_W65816_DATA32 ||
+             rtype == R_W65816_IMM16 || rtype == R_W65816_BANK16) &&
+            (target & 0xFF0000u) == 0u && target != 0u) {
+            uint8_t cnt = (rtype == R_W65816_IMM24 || rtype == R_W65816_DATA32) ? 3 : 2;
+            for (uint8_t i = 0; i < cnt; ++i)
+                buf[off + i] = 0;
+            InterImm24Site s;
+            s.patchSeg  = static_cast<uint16_t>(patchSeg);
+            s.patchOff  = static_cast<uint16_t>(patchAddr - pseg.base);
+            s.targetSeg = 1;
+            s.targetOff = static_cast<uint16_t>(target);
+            s.byteCnt   = cnt;
+            s.bitShift  = (rtype == R_W65816_BANK16) ? 16 : 0;
+            gInterImm24Sites.push_back(s);
+            return;
+        }
         applyReloc(buf, off, patchAddr, target, rtype, symName);
         // Also push into the per-seg list with the same gates as
         // recordCRelocSite (target in same bank as textBase and
@@ -2570,6 +2611,7 @@ int main(int argc, char **argv) {
         L.bssBase, L.bssSize,
         outPath.c_str(), image.size());
     if (L.segments.size() > 1) {
+        std::fprintf(stderr, " [dbg: textReloc=%lu bare=%lu]", gDbgTextCalls, gDbgBareCalls);
         std::fprintf(stderr, " + %zu extra segments",
                      L.segments.size() - 1);
         for (size_t k = 1; k < L.segments.size(); ++k) {