Re: [Xen-devel] [PATCH 10/27] xen: make sure swiotlb allocationisphysically contigious

[Jeremy Fitzhardinge]

Jan Beulich wrote:
>  
> While on native using alloc_bootmem_low_pages() is a requirement here,
> on Xen this should explicitly not be used, as we realized just a couple of
> days ago:

Which conversation was this?

>  The way the bootmem allocator works, running out of space
> below 4Gb is pretty easy on machines with lots of memory, and since the
> swiotlb is a requirement for Dom0, the risk of allocation failures must be
> kept as low as possible.
>   

Are we talking about a 32 or 64 bit dom0 here?  If its 32-bit, then yes, 
low memory is a precious resource, but I don't see why that depends on 
the total amount of memory.  And if its 64-bit, why is below-4G 
particularly constrained?  That would only matter for 32-bit devices?

   J
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