Commit:     033b8ffe3f1ea8174d51d125838ac6deea60f63f
Parent:     84aa462e2c2cd1b921f6b8e283f8d41666e02e8e
Author:     Mike Westerhof <[EMAIL PROTECTED]>
AuthorDate: Thu Oct 11 03:18:14 2007 +0100
Committer:  Russell King <[EMAIL PROTECTED]>
CommitDate: Fri Oct 12 23:43:48 2007 +0100

    [ARM] 4599/1: Preserve ATAG list for use with kexec (2.6.23)
    This patch resolves a kexec boot failure that can occur because
    no ATAGs are passed in to the kexec'd kernel. Currently the
    newly-kexec'd kernel may fail if it requires specific ATAGs, or
    it may fail because the fixed memory location at which it expects
    to find the ATAGs may contain random data instead of ATAGs.
    The patch ensures that any ATAGs passed to the current kernel
    at boot time are copied to a static buffer, and are copied back
    when kexec copies the new kernel into place. Thus the new
    kernel sees the same ATAGs from kexec and the boot loader.
    The boot parameters are copied without regard to type, content,
    or length -- this patch's scope is limited soley to saving and
    restoring a fixed-size block of memory containing the kernel's
    boot parameters. Additional functionality to examine, alter, or
    replace the ATAGs (using kexec, for example) can be implemented
    by manipulating the static buffer containing the preserved ATAGs.
    Note: the size of the buffer (1.5KB) is selected to comfortably
    hold one of each ATAG type, including a maximum-length command
    line and the maximum number of ATAG_MEM structures currently
    supported by the kernel. Should an ATAG list exceed that limit,
    the list will be silently truncated to that limit (to do other-
    wise at that point in the boot process would make a simple
    problem exceedingly complicated).
    [Note: this is the same patch as 4579, modified to accomodate
    the ATAG changes introduced in 2.6.23]
    Signed-off-by: Mike Westerhof <mwester at>
    Signed-off-by: Russell King <[EMAIL PROTECTED]>
 arch/arm/kernel/relocate_kernel.S |   29 ++++++++++++++++++++++++++++-
 arch/arm/kernel/setup.c           |   30 ++++++++++++++++++++++++++++++
 include/asm-arm/kexec.h           |    2 ++
 3 files changed, 60 insertions(+), 1 deletions(-)

diff --git a/arch/arm/kernel/relocate_kernel.S 
index 7baadae..062c111 100644
--- a/arch/arm/kernel/relocate_kernel.S
+++ b/arch/arm/kernel/relocate_kernel.S
@@ -7,6 +7,23 @@
        .globl relocate_new_kernel
+       /* Move boot params back to where the kernel expects them */
+       ldr     r0,kexec_boot_params_address
+       teq     r0,#0
+       beq     8f
+       ldr     r1,kexec_boot_params_copy
+       mov     r6,#KEXEC_BOOT_PARAMS_SIZE/4
+       ldr     r5,[r1],#4
+       str     r5,[r0],#4
+       subs    r6,r6,#1
+       bne     7b
+       /* Boot params moved, now go on with the kernel */
        ldr     r0,kexec_indirection_page
        ldr     r1,kexec_start_address
@@ -50,7 +67,7 @@ relocate_new_kernel:
        mov lr,r1
        mov r0,#0
        ldr r1,kexec_mach_type
-       mov r2,#0
+       ldr r2,kexec_boot_params_address
        mov pc,lr
        .globl kexec_start_address
@@ -65,6 +82,16 @@ kexec_indirection_page:
        .long   0x0
+       /* phy addr where new kernel will expect to find boot params */
+       .globl kexec_boot_params_address
+       .long   0x0
+       /* phy addr where old kernel put a copy of orig boot params */
+       .globl kexec_boot_params_copy
+       .long   0x0
        .globl relocate_new_kernel_size
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index efac7df..bf56eb3 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -24,6 +24,7 @@
 #include <linux/interrupt.h>
 #include <linux/smp.h>
 #include <linux/fs.h>
+#include <linux/kexec.h>
 #include <asm/cpu.h>
 #include <asm/elf.h>
@@ -783,6 +784,23 @@ static int __init customize_machine(void)
+/* Physical addr of where the boot params should be for this machine */
+extern unsigned long kexec_boot_params_address;
+/* Physical addr of the buffer into which the boot params are copied */
+extern unsigned long kexec_boot_params_copy;
+/* Pointer to the boot params buffer, for manipulation and display */
+unsigned long kexec_boot_params;
+/* The buffer itself - make sure it is sized correctly */
+static unsigned long kexec_boot_params_buf[(KEXEC_BOOT_PARAMS_SIZE + 3) / 4];
 void __init setup_arch(char **cmdline_p)
        struct tag *tags = (struct tag *)&init_tags;
@@ -801,6 +819,18 @@ void __init setup_arch(char **cmdline_p)
        else if (mdesc->boot_params)
                tags = phys_to_virt(mdesc->boot_params);
+       kexec_boot_params_copy = virt_to_phys(kexec_boot_params_buf);
+       kexec_boot_params = (unsigned long)kexec_boot_params_buf;
+       if (__atags_pointer) {
+               kexec_boot_params_address = __atags_pointer;
+               memcpy((void *)kexec_boot_params, tags, KEXEC_BOOT_PARAMS_SIZE);
+       } else if (mdesc->boot_params) {
+               kexec_boot_params_address = mdesc->boot_params;
+               memcpy((void *)kexec_boot_params, tags, KEXEC_BOOT_PARAMS_SIZE);
+       }
         * If we have the old style parameters, convert them to
         * a tag list.
diff --git a/include/asm-arm/kexec.h b/include/asm-arm/kexec.h
index b5b030e..46dcc4d 100644
--- a/include/asm-arm/kexec.h
+++ b/include/asm-arm/kexec.h
@@ -14,6 +14,8 @@
 #ifndef __ASSEMBLY__
 struct kimage;
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