From: Will Sowerbutts <will@sowerbutts.com>
Date: Sat, 27 Dec 2014 11:26:25 +0000 (+0000)
Subject: Kernel: Bug fix -- on system call, touch kernel_flag only after switching to the... 
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=4154d9829c22a395fefdc811c6d56eff4cc26eaa;p=FUZIX.git

Kernel: Bug fix -- on system call, touch kernel_flag only after switching to the kernel memory bank
---

diff --git a/Kernel/lowlevel-z80.s b/Kernel/lowlevel-z80.s
index 3088cdc2..c43c4f60 100644
--- a/Kernel/lowlevel-z80.s
+++ b/Kernel/lowlevel-z80.s
@@ -77,10 +77,6 @@ unix_syscall_entry:
         push ix
         push iy
 
-	; make sure the interrupt logic knows we are in kernel mode
-	ld a, #1
-	ld (_kernel_flag), a
-
         ; locate function call arguments on the userspace stack
         ld hl, #18     ; 16 bytes machine state, plus 2 bytes return address
         add hl, sp
@@ -103,6 +99,10 @@ unix_syscall_entry:
         ; map in kernel keeping common
 	call map_kernel
 
+	; make sure the interrupt logic knows we are in kernel mode (flag lives in kernel bank)
+	ld a, #1
+	ld (_kernel_flag), a
+
         ; re-enable interrupts
         ei