> But the /dev/crash driver does require small modifications to the kernel source,
> primarily to EXPORT_SYMBOL_GPL() the page_is_ram() function.
Interesting -- FWIW, the EXPORT_SYMBOL_GPL() requirement for page_is_ram()
may no longer be required if an analogous, static, version of page_is_ram()
were to be written into the crash driver itself -- and that static version
could use the e820_any_mapped() function, which is EXPORT_SYMBOL_GPL() in
the upstream kernel:
/*
* This function checks if any part of the range <start,end> is mapped
* with type.
*/
int
e820_any_mapped(u64 start, u64 end, unsigned type)
{
int i;
for (i = 0; i < e820.nr_map; i++) {
const struct e820entry *ei = &e820.map[i];
if (type && ei->type != type)
continue;
if (ei->addr >= end || ei->addr + ei->size <= start)
continue;
return 1;
}
return 0;
}
EXPORT_SYMBOL_GPL(e820_any_mapped);
For that matter, e820_any_mapped() is also in RHEL5. But it was not
in the 2.6.9-based RHEL4 kernel, which was what the RHEL5 version of the
crash driver was based upon.
But RHEL5 also has modified the x86-only page_is_ram() to check for efi_enabled,
and if it's set, to use the "memmap" efi_memory_map instead of the e820 map.
Although, that's not done upstream.
Anyway, just another data point...
Dave
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