diff options
| -rw-r--r-- | fixup.S | 84 | ||||
| -rw-r--r-- | fixup.bin | bin | 0 -> 84 bytes | |||
| -rw-r--r-- | fixup.txt | 17 |
3 files changed, 101 insertions, 0 deletions
diff --git a/fixup.S b/fixup.S new file mode 100644 index 000000000000..42d27fc0c949 --- /dev/null +++ b/fixup.S @@ -0,0 +1,84 @@ +/* Copyright (c) 2013, The Linux Foundation. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following + * disclaimer in the documentation and/or other materials provided + * with the distribution. + * * Neither the name of The Linux Foundation nor the names of its + * contributors may be used to endorse or promote products derived + * from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS + * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR + * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, + * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE + * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN + * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + */ +/* Fixup the atags for dragonboard (and possibly other targets). */ +/* + * The bootloader on some targets passes an ATAG in that sets the + * first memory region to be 2MB after the actual start of memory. + * With newer upstream kernels, the PHYS_OFFSET must be a multiple of + * a large boundary (currently 128MB). Without devicetree, we work + * around this with an early init hook, and a fixup that adds a + * reservation. These hooks don't run in time to fix it in Device + * tree. + * + * The following code can be prepended to the zImage. It adjusts the + * memory atag back down to the actual start of memory. The + * assumption is that the device tree will describe the necessary + * memory reservation. The zImage is relocatable, so it is easy to + * prepend this code. + */ + + /* Figure out what the broken mem tag would be */ + mov r8, pc + and r8, r8, #0xf8000000 + add r8, r8, #0x00200000 + + /* R2 is where the atags are passed. r5 on are scratch. */ + mov r5, r2 + ldr r7, .tag_mem + +.next: + /* Load the tag, and check. */ + ldr r6, [r5, #4] + cmp r6, #0 + beq .done + + /* Is the a 'mem' tag. */ + cmp r6, r7 + bne .not_mem + + /* Is this memory base what we want? */ + ldr r6, [r5, #12] + cmp r6, r8 + + subeq r6, r6, #0x200000 + streq r6, [r5, #12] + ldreq r6, [r5, #8] + addeq r6, r6, #0x200000 + streq r6, [r5, #8] + +.not_mem: + /* Move r5 to the next tag. */ + ldr r6, [r5, #0] + add r5, r5, r6, asl #2 + b .next + +.tag_mem: + .word 0x54410002 + +.done: diff --git a/fixup.bin b/fixup.bin Binary files differnew file mode 100644 index 000000000000..67f2a17eaaa8 --- /dev/null +++ b/fixup.bin diff --git a/fixup.txt b/fixup.txt new file mode 100644 index 000000000000..07bcb3c52a0d --- /dev/null +++ b/fixup.txt @@ -0,0 +1,17 @@ + +Fixup loader to boot mainline on Qualcomm platforms that needs adjustment of +ATAG MEM. + +Found at [1], built by issuing: + + arm-eabi-as -o fixup.o fixup.S + arm-eabi-objcopy -O binary fixup.o fixup.bin + + +Use by concatenating together with zImage: + + cat fixup.bin arch/arm/boot/zImage > zImage + + +[1] https://www.codeaurora.org/cgit/quic/kernel/skales/tree/atag-fix/fixup.S + |