Author: ian
Date: Sat Jan 2 22:31:14 2016
New Revision: 293063
URL: https://svnweb.freebsd.org/changeset/base/293063
Log:
Work around problems that happen when there is ram at the end of the
physical address space.
Modified:
head/sys/arm/arm/physmem.c
Modified: head/sys/arm/arm/physmem.c
==============================================================================
--- head/sys/arm/arm/physmem.c Sat Jan 2 22:04:37 2016 (r293062)
+++ head/sys/arm/arm/physmem.c Sat Jan 2 22:31:14 2016 (r293063)
@@ -280,10 +280,24 @@ arm_physmem_hardware_region(vm_paddr_t p
/*
* Filter out the page at PA 0x00000000. The VM can't handle it, as
* pmap_extract() == 0 means failure.
+ *
+ * Also filter out the page at the end of the physical address space --
+ * if addr is non-zero and addr+size is zero that means we wrapped to
+ * the next byte beyond what vm_paddr_t can express. The calculations
+ * in vm_page_startup() are going to have the same problem, so just work
+ * around it by leaving the last page out.
+ *
+ * XXX This just in: subtract out a whole megabyte, not just 1 page.
+ * Reducing the size by anything less than 1MB results in a NULL pointer
+ * deref in _vm_map_lock_read() very early in startup. Better to give
+ * up a whole megabyte than leave some folks with an unusable system
+ * while we investigate.
*/
if (pa == 0) {
pa = PAGE_SIZE;
sz -= PAGE_SIZE;
+ } else if (pa + sz == 0) {
+ sz -= 1024 * 1024;
}
/*
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