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From: Oleksij Rempel <o.rempel@pengutronix.de>
To: antonynpavlov@gmail.com, barebox@lists.infradead.org
Cc: Oleksij Rempel <o.rempel@pengutronix.de>
Subject: [PATCH v2] MIPS: remove .bss to __rel_start overlay
Date: Tue, 28 Jan 2020 19:15:28 +0100	[thread overview]
Message-ID: <20200128181528.10976-1-o.rempel@pengutronix.de> (raw)

.bss __rel_start (OVERLAY) was used to optimize RAM size used by
barebox. Since .bss and __rel_start overlap, we should clear bss only
after __rel_start was used. Following patch changed initialization
sequence to clear .bss before __rel_start:
1e5aef61fc6a444 ("MIPS: reloc: init bss and cpu")

This make relocation buffer unusable and broke relocation with different
symptoms reported by Antony Pavlov <antonynpavlov@gmail.com>:
  * iomem output has no information on sdram regions, so memtest is unusable;
  * pc = 0xa081232c, relocation does not work, barebox is located with 8M offset
    from start of RAM. The board has 256M and relocation routine
    should move barebox code much higher;
  * pc = 0xa081232c, so barebox code works from KSEG1 not from KSEG0 as MMU=y option implies.

There is a choice of moving .bss clear sequence after __rel_start or
remove this optimization. Since the use of this optimization is minimal
and danger to trap in to similar issue is still high, i prefer to remove
this optimization.

Reported-by: Antony Pavlov <antonynpavlov@gmail.com>
Fixes: 1e5aef61fc6a444 ("MIPS: reloc: init bss and cpu")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 arch/mips/lib/barebox.lds.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/mips/lib/barebox.lds.S b/arch/mips/lib/barebox.lds.S
index 693a778980..c954df41f3 100644
--- a/arch/mips/lib/barebox.lds.S
+++ b/arch/mips/lib/barebox.lds.S
@@ -59,7 +59,7 @@ SECTIONS
 
 	_end = .;
 
-	.bss __rel_start (OVERLAY) : {
+	.bss : {
 		__bss_start = .;
 		*(.sbss.*)
 		*(.bss.*)
-- 
2.25.0


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                 reply	other threads:[~2020-01-28 18:15 UTC|newest]

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