disable mfn_is_ram

This patch disables the mfn_is_ram check in mini-os. The current check is insufficient and fails on some systems with larger than 4gb memory.

@@ -850,6 +850,8 @@ unsigned long alloc_contig_pages(int order, unsigned

int addr_bits)
static long system_ram_end_mfn;
int mfn_is_ram(unsigned long mfn)
{
+ /* This is broken on systems with large ammounts of ram. Always
return 0 for now */

+    return 0;
     /* very crude check if a given MFN is memory or not. Probably should
      * make this a little more sophisticated ;) */
     return (mfn <= system_ram_end_mfn) ? 1 : 0;

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And it is only used for checks, not for actual decisions.

Samuel

How does it fail? What are the symptoms? What are the inputs to this function which cause it to fail?

It's made completely useless here though, why not either fix it or remove it altogether?

There's certainly no reason to leave the dead code after the return statement.

When there is more than 4gb memory, there is IO memory between e.g. 3gb and 4gb, which will be considered as RAM.

We can probably just remove the check in __do_ioremap, which AFAIK is the only call.

Samuel