[OpenBIOS] [PATCHv2 4/4] SPARC32: clear physical memory upon startup

[Mark Cave-Ayland]

This is to work around a bug in Solaris which appears not to explicitly clear
some of its internal kmem structures (particularly its pagelists) on boot. The
result of this is that Solaris will initially boot fine, until a reboot/reset
is initiated.

When this occurs, the kmem structures contain whatever junk was previously left
in memory during initialisation causing a panic. The fix is to clear physical
memory on startup (as OBP appears to do) so that the kmem intialisation code
behaves correctly.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland at ilande.co.uk>
---
 openbios-devel/arch/sparc32/entry.S |   37 +++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/openbios-devel/arch/sparc32/entry.S b/openbios-devel/arch/sparc32/entry.S
index d95a308..72cb338 100644
--- a/openbios-devel/arch/sparc32/entry.S
+++ b/openbios-devel/arch/sparc32/entry.S
@@ -122,7 +122,44 @@ entry:
         or      %g3, %g4, %g1
         ! %g1 contains end of memory
 
+        ! Get kernel address from configuration device
+        ! NB: little endian format
+        mov     FW_CFG_KERNEL_ADDR, %g2
+        sub     %g5, 2, %g5
+        stha    %g2, [%g5] CFG_ASI
+        add     %g5, 2, %g5
+        lduba   [%g5] CFG_ASI, %g4
+
+        lduba   [%g5] CFG_ASI, %g3
+        sll     %g3, 8, %g3
+        or      %g3, %g4, %g4
+
+        lduba   [%g5] CFG_ASI, %g3
+        sll     %g3, 16, %g3
+        or      %g3, %g4, %g4
+
+        lduba   [%g5] CFG_ASI, %g3
+        sll     %g3, 24, %g3
+        or      %g3, %g4, %g4
+
+        ! If kernel address is set, don't clear from base of RAM in order to
+        ! leave the kernel image intact
+        mov     0, %g6
+        cmp     %g4, 0
+        beq     clear_mem
+         nop
+
+        ! Start from 16M
+        set     0x1000000, %g6
+
+clear_mem:
+        sta     %g0, [%g6] ASI_M_BYPASS
+        add     %g6, 0x4, %g6
+        cmp     %g6, %g1
+        bl      clear_mem
+         nop
 
+clear_done:
         ! Start of private memory in %g6
         set     0x2000, %g3
         sub     %g1, %g3, %g6
-- 
1.7.10.4