linux-kernel - [PATCH] openrisc: Add support for external initrd images

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Message-Id: <20200704211136.601768-1-shorne@gmail.com>
Date:   Sun,  5 Jul 2020 06:11:34 +0900
From:   Stafford Horne <shorne@...il.com>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Stafford Horne <shorne@...il.com>,
        Mateusz Holenko <mholenko@...micro.com>,
        Jonas Bonn <jonas@...thpole.se>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Borislav Petkov <bp@...e.de>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Kees Cook <keescook@...omium.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        openrisc@...ts.librecores.org
Subject: [PATCH] openrisc: Add support for external initrd images

In OpenRISC we set the initrd_start and initrd_end based on the symbols
we setup in vmlinux.lds.S.  However, this is not needed if we use the
generic linker description in INIT_DATA_SECTION.

Removing our own initrd setup reduces code, but also the generic code
supports loading external initrd images.  A bootloader can load a rootfs
image into memory and we can configure devicetree to load it with:

        chosen {
                bootargs = "earlycon";
                stdout-path = "uart0:115200";
                linux,initrd-start = < 0x08000100 >;
                linux,initrd-end = < 0x08200000 >;
        };

Reported-by: Mateusz Holenko <mholenko@...micro.com>
Signed-off-by: Stafford Horne <shorne@...il.com>
---
 arch/openrisc/kernel/setup.c       |  8 +++++---
 arch/openrisc/kernel/vmlinux.lds.S | 12 ------------
 2 files changed, 5 insertions(+), 15 deletions(-)

diff --git a/arch/openrisc/kernel/setup.c b/arch/openrisc/kernel/setup.c
index 8aa438e1f51f..b18e775f8be3 100644
--- a/arch/openrisc/kernel/setup.c
+++ b/arch/openrisc/kernel/setup.c
@@ -292,13 +292,15 @@ void __init setup_arch(char **cmdline_p)
 	init_mm.brk = (unsigned long)_end;
 
 #ifdef CONFIG_BLK_DEV_INITRD
-	initrd_start = (unsigned long)&__initrd_start;
-	initrd_end = (unsigned long)&__initrd_end;
 	if (initrd_start == initrd_end) {
+		printk(KERN_INFO "Initial ramdisk not found\n");
 		initrd_start = 0;
 		initrd_end = 0;
+	} else {
+		printk(KERN_INFO "Initial ramdisk at: 0x%p (%lu bytes)\n",
+		       (void *)(initrd_start), initrd_end - initrd_start);
+		initrd_below_start_ok = 1;
 	}
-	initrd_below_start_ok = 1;
 #endif
 
 	/* setup memblock allocator */
diff --git a/arch/openrisc/kernel/vmlinux.lds.S b/arch/openrisc/kernel/vmlinux.lds.S
index 60449fd7f16f..22fbc5fb24b3 100644
--- a/arch/openrisc/kernel/vmlinux.lds.S
+++ b/arch/openrisc/kernel/vmlinux.lds.S
@@ -96,18 +96,6 @@ SECTIONS
 
         __init_end = .;
 
-	. = ALIGN(PAGE_SIZE);
-	.initrd			: AT(ADDR(.initrd) - LOAD_OFFSET)
-	{
-		__initrd_start = .;
-		*(.initrd)
-		__initrd_end = .;
-		FILL (0);
-                . = ALIGN (PAGE_SIZE);
-	}
-
-        __vmlinux_end = .;            /* last address of the physical file */
-
 	BSS_SECTION(0, 0, 0x20)
 
         _end = .;
-- 
2.26.2