[RFC] updating lmb.memory information for hot mem add/remove

Badari Pulavarty pbadari at us.ibm.com
Sat Mar 1 04:56:56 EST 2008


Hi,

I am wondering if you could give me your opinion on how to proceed
(before I code too much).

eHEA driver writers wants to know what the memory layout is - where the
holes are and where the reserved memory is. They can get this from
parsing through the device-tree every time, but it would be too
expensive. And also, they would like to get information for contiguous
ranges (instead of 16MB chunks).

Since we already have this information at boot time in lmb.memory, 
lmb.reserve - would it be okay to update those for hotplug mem
add/remove ? Of course, all the routines which handles updates 
(lmb_add() etc..) are available only at boot (__init). I could
change that. Is it acceptable ?

Other way to handle the issue is to come up with arch-neutral
way of representing the memory layout. x86-64 and ia64 shows
this information in /proc/iomem (even there is in chunks not 
combined).

Ideas ? Would it be acceptable if I update lmb.memory for add/remove
memory ? Am I missing something ?

Thanks,
Badari




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