Re: Big Fix for 2.2.1

[MOLNAR Ingo]

On Tue, 26 Jan 1999, Linus Torvalds wrote:

> 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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