> ie the "legacy ISA region" is currently (for backwards compatibility
> reasons) not required to be io-remapped.
>
> Look at various network drivers for example - your patches probably break
> a noticeable number of them.
the attached patch works for me, but i guess it's definitely too ugly to
live in the stock kernel. Anyway, if anyone wants to have non-power-2
-PAGE_OFFSET, this patch might help...
-- mingo
--- linux/include/asm-i386/io.h.orig Tue Jan 26 20:56:45 1999
+++ linux/include/asm-i386/io.h Wed Jan 27 10:55:16 1999
@@ -101,8 +101,46 @@
#include <linux/vmalloc.h>
#include <asm/page.h>
-#define __io_virt(x) ((void *)(PAGE_OFFSET | (unsigned long)(x)))
-#define __io_phys(x) ((unsigned long)(x) & ~PAGE_OFFSET)
+/*
+ * ISA IO legacy address space 0-1M
+ */
+#define __ISA_LIMIT 0x100000UL
+
+/*
+ * __io_virt() has to accept the 0-1M address space for legacy
+ * drivers. We will fix this in 2.3 to be an identity mapping.
+ */
+#define __io_virt(x) \
+({ void * __ret; \
+ if ((unsigned long)x < __ISA_LIMIT) \
+ /* \
+ * In 2.3 we want to print a warning here \
+ */ \
+__broken: \
+ __ret = (void *)(PAGE_OFFSET + (unsigned long)(x)); \
+ else { \
+ if ((unsigned long)x < PAGE_OFFSET) \
+ /* \
+ * and here. (yes this gets triggered) \
+ */ \
+ goto __broken; \
+ __ret = (void*) x; \
+ } \
+ __ret; \
+})
+
+/*
+ * __io_phys() has no legacy uses.
+ */
+#define __io_phys(x) \
+({ unsigned long __ret; \
+ if ((unsigned long)x < PAGE_OFFSET) \
+ __ret = (unsigned long)(x); \
+ else \
+ __ret = (unsigned long)(x) - PAGE_OFFSET; \
+ __ret; \
+})
+
/*
* Change virtual addresses to physical addresses and vv.
* These are pretty trivial
-
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