Arnd Bergmann wrote: > > On Wednesday 12 June 2013, Subash Patel wrote: > > > I would definitely leave on exynos5440 support in defconfig. It's not > a > > > lot of extra code, and if you have a system with less than 4GB memory, > > > you really don't want to enable LPAE because of the overhead. > > > > Even if we have <= 4GB memory, and the system designers have placed the > > memory banks in addresses > 2^32 bytes, then we need LPAE support. I > > think we may have such systems in future. So memory capacity is not the > > only parameter to judge if we need to enable LPAE or not. > > Yes, but that wasn't the point. You can always build systems with > exynos5440 that don't need LPAE, so we should not assume that it is > not a reasonable configuration. > Agreed. > I would certainly advise system designers to put all the RAM and I/O > into normally addressable locations if possible to avoid the need > for LPAE, but of course that isn't always possible. > Yes, same here. Actually, some IPs sometimes can request to alloc/use something like dma buffer over 32 bit area after LPAE enabling, but will not be happened without LPAE. > We should probably have someone measure the performance impact > of LPAE as well. If it's less than a few percent, we might not > care all that much. > Yes, after testing on exynos5440 board, LPAE doesn't cause any performance degradation with lmbench tool. - Kukjin -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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