diff --git a/arch/risc-v/src/eic7700x/eic7700x_mm_init.c b/arch/risc-v/src/eic7700x/eic7700x_mm_init.c
index 2b68d6c721c..60ea2ee6f6d 100644
--- a/arch/risc-v/src/eic7700x/eic7700x_mm_init.c
+++ b/arch/risc-v/src/eic7700x/eic7700x_mm_init.c
@@ -237,8 +237,16 @@ void eic7700x_kernel_mappings(void)
   binfo("map kernel text\n");
   map_region(KFLASH_START, KFLASH_START, KFLASH_SIZE, MMU_KTEXT_FLAGS);
 
+  /* The kernel data region is mapped with 2 MiB pages rather than through
+   * map_region()'s 4 KiB ones.  Everything in it, data, bss, the page
+   * tables, the idle stacks and the whole kernel heap, carries the same
+   * permissions, so the finer granularity buys nothing while costing one L3
+   * slab per 2 MiB from a pool of exactly two.
+   */
+
   binfo("map kernel data\n");
-  map_region(KSRAM_START, KSRAM_START, KSRAM_SIZE, MMU_KDATA_FLAGS);
+  mmu_ln_map_region(2, PGT_L2_VBASE, KSRAM_START, KSRAM_START,
+                    KSRAM_SIZE, MMU_KDATA_FLAGS);
 
   /* Connect the L1 and L2 page tables for the kernel text and data */
 
@@ -250,6 +258,14 @@ void eic7700x_kernel_mappings(void)
   binfo("map the page pool\n");
   mmu_ln_map_region(2, PGT_L2_VBASE, PGPOOL_START, PGPOOL_START,
                     PGPOOL_SIZE, MMU_KDATA_FLAGS);
+
+  /* Map the RAM disk.  The page pool no longer covers it, so it needs its
+   * own mapping or the first read of /dev/ram0 faults.
+   */
+
+  binfo("map the RAM disk\n");
+  mmu_ln_map_region(2, PGT_L2_VBASE, RAMDISK_START, RAMDISK_START,
+                    RAMDISK_SIZE, MMU_KDATA_FLAGS);
 }
 
 /****************************************************************************
diff --git a/arch/risc-v/src/eic7700x/eic7700x_pgalloc.c b/arch/risc-v/src/eic7700x/eic7700x_pgalloc.c
index 463b39d6ccf..81095a6c4e7 100644
--- a/arch/risc-v/src/eic7700x/eic7700x_pgalloc.c
+++ b/arch/risc-v/src/eic7700x/eic7700x_pgalloc.c
@@ -31,6 +31,21 @@
 #include <nuttx/debug.h>
 #include <arch/board/board_memorymap.h>
 
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* The granule allocator behind mm_pgalloc() counts its pages in a uint16_t,
+ * and gran_initialize() refuses a pool with more than UINT16_MAX of them,
+ * returning NULL.  mm_pginitialize() then asserts, so an oversized pool is a
+ * board that does not boot rather than a board with less memory than asked
+ * for.  See mm/mm_gran/mm_gran.h and mm/mm_gran/mm_graninit.c.
+ */
+
+#if (CONFIG_ARCH_PGPOOL_SIZE / CONFIG_MM_PGSIZE) > 65535
+#  error "Page pool has more pages than the granule allocator can count"
+#endif
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -50,6 +65,18 @@ void up_allocate_pgheap(void **heap_start, size_t *heap_size)
 {
   DEBUGASSERT(heap_start && heap_size);
 
+  /* The linker script and Kconfig describe this pool separately, and both
+   * descriptions are used: the size below comes from the linker, while
+   * riscv_pgvaddr() decides whether a page is in the pool using the Kconfig
+   * values.  If they disagree, pages outside the smaller of the two get a
+   * virtual address of zero and are then written through, which on this SoC
+   * lands on the identity mapped low memory rather than faulting.  Say so
+   * here instead of finding out that way.
+   */
+
+  DEBUGASSERT(PGPOOL_START == CONFIG_ARCH_PGPOOL_PBASE);
+  DEBUGASSERT(PGPOOL_SIZE  == CONFIG_ARCH_PGPOOL_SIZE);
+
   *heap_start = (void *)PGPOOL_START;
   *heap_size  = (size_t)PGPOOL_SIZE;
 }