On Wed, 2008-08-06 at 00:02 -0600, Grant Likely wrote:
From: Grant Likely <redacted>
ioremap_bat() is useful for things like mapping SoC internally memory mapped
register and early text because it allows mappings to devices to be setup
early in the boot process where they are needed, and the mappings persist
after the MMU is configured.
Without ioremap_bat(), setting up the MMU would cause the early text
mappings to get lost and mostly likely result in a kernel panic on the next
attempt at output.
Signed-off-by: Grant Likely <redacted>
---
First comment, make the name more generic. This facility could be
implemented on processors without BATs using different techniques.
Maybe ioremap_block() or ioremap_early() or something like that.
quoted hunk ↗ jump to hunk
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index 066e65c..7b25b57 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -113,6 +113,15 @@ notrace unsigned long __init early_init(unsigned long dt_ptr)
*/
notrace void __init machine_init(unsigned long dt_ptr, unsigned long phys)
{
+ /* Do the bare minimum to start allocting from the IO region so
+ * that ioremap_bat() works */
+#ifdef CONFIG_HIGHMEM
+ ioremap_base = PKMAP_BASE;
+#else
+ ioremap_base = 0xfe000000UL; /* for now, could be 0xfffff000 */
+#endif /* CONFIG_HIGHMEM */
+ ioremap_bot = ioremap_base;
+
Can't these be statically initialized ? If not, then do a function call
to mm/ please. Something like mm_init_early().
quoted hunk ↗ jump to hunk
+ /* BAT mappings must be 128k aligned */
+ if (addr != _ALIGN_DOWN(addr, 128 << 10))
+ return NULL;
Mustn't they be naturally aligned on their size ?
Cheers,
Ben.