entrydump: trivial program to probe PXE entry conditions

Small debugging hack program to probe the PXE stack entry
conditions.  This is mostly useful when developing a PXE stack,
but might possibly be handy for finding workarounds for a stack,
too.

2 files changed, 63 insertions, 1 deletions

diff --git a/com32/samples/Makefile b/com32/samples/Makefile
index 7f5ea190..482769ef 100644
--- a/com32/samples/Makefile
+++ b/com32/samples/Makefile
@@ -21,7 +21,7 @@ all:	hello.c32 cat.c32 resolv.c32 serialinfo.c32 \
 	localboot.c32 \
 	fancyhello.c32 fancyhello.lnx \
 	keytest.c32 keytest.lnx \
-	advdump.c32
+	advdump.c32 entrydump.c32
 
 tidy dist:
 	rm -f *.o *.lo *.a *.lst *.elf .*.d *.tmp
diff --git a/com32/samples/entrydump.c b/com32/samples/entrydump.c
new file mode 100644
index 00000000..b36a30d3
--- /dev/null
+++ b/com32/samples/entrydump.c
@@ -0,0 +1,62 @@
+/* ----------------------------------------------------------------------- *
+ *
+ *   Copyright 2004-2008 H. Peter Anvin - All Rights Reserved
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
+ *   Boston MA 02111-1307, USA; either version 2 of the License, or
+ *   (at your option) any later version; incorporated herein by reference.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * entry.c
+ *
+ * Dump the entry point registers
+ */
+
+#include <string.h>
+#include <stdio.h>
+#include <inttypes.h>
+#include <console.h>
+#include <syslinux/config.h>
+
+struct stack_frame {
+  uint16_t gs, fs, es, ds;
+  uint32_t edi, esi, ebp, esp;
+  uint32_t ebx, edx, ecx, eax;
+  uint32_t eflags;
+  uint16_t ret_ip, ret_cs;
+  uint16_t pxe_ip, pxe_cs;
+};
+
+int main(void)
+{
+  const union syslinux_derivative_info *di;
+  const struct stack_frame *sf;
+  int i;
+  const unsigned char *p;
+
+  openconsole(&dev_null_r, &dev_stdcon_w);
+
+  di = syslinux_derivative_info();
+
+  if (di->c.filesystem != SYSLINUX_FS_PXELINUX) {
+    printf("Not running under PXELINUX (fs = %02x)\n", di->c.filesystem);
+    return 1;
+  }
+
+  sf = (const struct stack_frame *)di->pxe.stack;
+
+  printf("EAX: %08x  EBX: %08x  ECX: %08x  EDX: %08x\n"
+	 "ESP: %08x  EBP: %08x  ESI: %08x  EDI: %08x\n"
+	 "SS: %04x   DS: %04x   ES: %04x   FS: %04x   GS:  %04x\n"
+	 "EFLAGS: %08x   RET: %04x:%04x   PXE: %04x:%04x\n",
+	 sf->eax, sf->ebx, sf->ecx, sf->edx,
+	 sf->esp+4, sf->ebp, sf->esi, sf->edi,
+	 di->rr.r.fs, sf->ds, sf->es, sf->fs, sf->gs,
+	 sf->eflags, sf->ret_cs, sf->ret_ip, sf->pxe_cs, sf->pxe_ip);
+
+  return 0;
+}