linux block: allow loading data up to 4GiB limit

Linux drivers are only limited by the DMA32 constraint, not by the directmap
constraint. But our segment order is currently set to
DMA < DMA32 < DIRECTMAP < HIGHMEM (since that is what we will have in 64bit
mode). In PAE mode this makes DMA32 limited to 800MiB.  Ideally we'd have
DMA < DIRECTMAP < DMA32 < HIGHMEM but that'd make the memory code more
complex, and we are to remove the Linux drivers anyway.  In the
meanwhile, In non-PAE mode we can just use HIGHMEM which is already
limited to 4GiB, that will do the work.

* linux/dev/glue/block.c (VM_PAGE_LINUX): New macro.
(device_read): Use VM_PAGE_LINUX instead of VM_PAGE_DMA32.

1 files changed, 8 insertions, 1 deletions

diff --git a/linux/dev/glue/block.c b/linux/dev/glue/block.c
index 709a8572..6730c5ec 100644
--- a/linux/dev/glue/block.c
+++ b/linux/dev/glue/block.c
@@ -84,6 +84,13 @@
 
 #include <linux/dev/glue/glue.h>
 
+#ifdef PAE
+#warning TODO: make DMA32 between DIRECTMAP and HIGHMEM
+#define VM_PAGE_LINUX VM_PAGE_DMA32
+#else
+#define VM_PAGE_LINUX VM_PAGE_HIGHMEM
+#endif
+
 /* This task queue is not used in Mach: just for fixing undefined symbols. */
 DECLARE_TASK_QUEUE (tq_disk);
 
@@ -1525,7 +1532,7 @@ device_read (void *d, ipc_port_t reply_port,
       /* Allocate and map pages.  */
       while (alloc_offset < trunc_page (offset) + len)
 	{
-	  while ((m = vm_page_grab (VM_PAGE_DMA32)) == 0)
+	  while ((m = vm_page_grab (VM_PAGE_LINUX)) == 0)
 	    VM_PAGE_WAIT (0);
 	  assert (! m->active && ! m->inactive);
 	  m->busy = TRUE;