Using RHEL4 U2's installer, a 64GB EM64T machine would panic on bootup with:
Kernel panic - not syncing: map_single: bounce buffer is not DMA'ble
The problem is because of mem_map using up most of the low memory (because of
64GB physical memory) and kernel is not able to allocate swiotlb buffer in low
memory. We have verified that things work fine by moving the swiotlb init earlier.
Patch from firstname.lastname@example.org attached.
Created attachment 121337 [details]
This patch will work but another/better solution is to move the mem_map above
the 4GB boundary. There is no reason that it needs to be at such a low address.
I'll work with Intel on creating a patch that does this.
This issue is on Red Hat Engineering's list of planned work items
for the upcoming Red Hat Enterprise Linux 4.4 release. Engineering
resources have been assigned and barring unforeseen circumstances, Red
Hat intends to include this item in the 4.4 release.
Created attachment 127908 [details]
Created attachment 127909 [details]
Created attachment 127910 [details]
Created attachment 127914 [details]
Updated patches attached.
committed in stream U4 build 34.25. A test kernel with this patch is available
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.