On Thu, Nov 14, 2013 at 10:59:05PM -0800, H. Peter Anvin wrote: > On 11/14/2013 10:55 PM, Yinghai Lu wrote: > > > > Why just asking distros to append ",high" in their installation > > program for 64bit by default? > > > [...] > > > > What is hpa's suggestion? > > > > Pretty much what you just said ;) I think crashkernel=X,high is not a good default choice for distros. Reserving memory high reserves 72MB (or more) low memory for swiotlb. We work hard to keep crashkernel memory amount low and currently reserve 128M by default. Now suddenly our total memory reservation will shoot to 200 MB if we choose ,high option. That's jump of more than 50%. It is not needed. We can do dumping operation successfully in *less* reserved memory by reserving memory below 4G. And hence crashkernel=,high is not a good default. Instead, crashkernel=X is a good default if we are ready to change semantics a bit. If sufficient crashkernel memory is not available in low memory area, look for it above 4G. This incurs penalty of 72M *only* if it has to and not by default on most of the systems. And this should solve jerry's problem too on *latest* kernels. For older kernels, we don't have ,high support. So using that is not an option. (until and unless somebody is ready to backport everything needed to boot old kernel above 4G). Thanks Vivek -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
