Alex Bennée <alex.ben...@linaro.org> writes:
> Schspa Shi <sch...@gmail.com> writes:
>
>> We use 32bit value for linux,initrd-[start/end], when we have
>> loader_start > 4GB, there will be a wrong initrd_start passed
>> to the kernel, and the kernel will report the following warning.
>>
>> [ 0.000000] ------------[ cut here ]------------
>> [ 0.000000] initrd not fully accessible via the linear mapping -- please
>> check your bootloader ...
>> [ 0.000000] WARNING: CPU: 0 PID: 0 at arch/arm64/mm/init.c:355
>> arm64_memblock_init+0x158/0x244
>> [ 0.000000] Modules linked in:
>> [ 0.000000] CPU: 0 PID: 0 Comm: swapper Tainted: G W
>> 6.1.0-rc3-13250-g30a0b95b1335-dirty #28
>> [ 0.000000] Hardware name: Horizon Sigi Virtual development board
>> (DT)
>
> Is this an out-of-tree board model?
>
Yes, this is a virtual board created by myself.
>> [ 0.000000] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS
>> BTYPE=--)
>> [ 0.000000] pc : arm64_memblock_init+0x158/0x244
>> [ 0.000000] lr : arm64_memblock_init+0x158/0x244
>> [ 0.000000] sp : ffff800009273df0
>> [ 0.000000] x29: ffff800009273df0 x28: 0000001000cc0010 x27:
>> 0000800000000000
>> [ 0.000000] x26: 000000000050a3e2 x25: ffff800008b46000 x24:
>> ffff800008b46000
>> [ 0.000000] x23: ffff800008a53000 x22: ffff800009420000 x21:
>> ffff800008a53000
>> [ 0.000000] x20: 0000000004000000 x19: 0000000004000000 x18:
>> 00000000ffff1020
>> [ 0.000000] x17: 6568632065736165 x16: 6c70202d2d20676e x15:
>> 697070616d207261
>> [ 0.000000] x14: 656e696c20656874 x13: 0a2e2e2e20726564 x12:
>> 0000000000000000
>> [ 0.000000] x11: 0000000000000000 x10: 00000000ffffffff x9 :
>> 0000000000000000
>> [ 0.000000] x8 : 0000000000000000 x7 : 796c6c756620746f x6 :
>> 6e20647274696e69
>> [ 0.000000] x5 : ffff8000093c7c47 x4 : ffff800008a2102f x3 :
>> ffff800009273a88
>> [ 0.000000] x2 : 80000000fffff038 x1 : 00000000000000c0 x0 :
>> 0000000000000056
>> [ 0.000000] Call trace:
>> [ 0.000000] arm64_memblock_init+0x158/0x244
>> [ 0.000000] setup_arch+0x164/0x1cc
>> [ 0.000000] start_kernel+0x94/0x4ac
>> [ 0.000000] __primary_switched+0xb4/0xbc
>> [ 0.000000] ---[ end trace 0000000000000000 ]---
>> [ 0.000000] Zone ranges:
>> [ 0.000000] DMA [mem 0x0000001000000000-0x0000001007ffffff]
>>
>> To fix it, we can change it to u64 type.
>>
>> Signed-off-by: Schspa Shi <sch...@gmail.com>
>> ---
>> hw/arm/boot.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/arm/boot.c b/hw/arm/boot.c
>> index 57efb61ee419..da719a4f8874 100644
>> --- a/hw/arm/boot.c
>> +++ b/hw/arm/boot.c
>> @@ -638,14 +638,14 @@ int arm_load_dtb(hwaddr addr, const struct
>> arm_boot_info *binfo,
>> }
>>
>> if (binfo->initrd_size) {
>> - rc = qemu_fdt_setprop_cell(fdt, "/chosen", "linux,initrd-start",
>> + rc = qemu_fdt_setprop_u64(fdt, "/chosen", "linux,initrd-start",
>> binfo->initrd_start);
>> if (rc < 0) {
>> fprintf(stderr, "couldn't set /chosen/linux,initrd-start\n");
>> goto fail;
>> }
>>
>> - rc = qemu_fdt_setprop_cell(fdt, "/chosen", "linux,initrd-end",
>> + rc = qemu_fdt_setprop_u64(fdt, "/chosen", "linux,initrd-end",
>> binfo->initrd_start +
>> binfo->initrd_size);
>> if (rc < 0) {
>> fprintf(stderr, "couldn't set /chosen/linux,initrd-end\n");
>
> On the face of things this seems fine because unlike the other linux
> properties they are not specified to be "expressed in #address-cells and
> #size-cells" but I do wonder how we got into the situation where the
> kernel and initrd ended up so high in the physical address space.
>
The reason why I faced this problem is there is no DRAM region below
4GB on the hardware. And I make this virtual board to have the same
memory layout as the hardware.
Although there is no something like #address-cells and #size-cells,
but Linux will handle the size correctly by calling the following code:
prop = of_get_flat_dt_prop(node, "linux,initrd-start", &len);
Please check the link at
Link: https://lore.kernel.org/all/20091105074724.10460.4083.stgit@angua/
Every Linux version support fdt on arm[64] platform should work without
problems.
> There is a whole comment in boot.c talking about keeping initrd within
> lowmem:
>
> /*
> * We want to put the initrd far enough into RAM that when the
> * kernel is uncompressed it will not clobber the initrd. However
> * on boards without much RAM we must ensure that we still leave
> * enough room for a decent sized initrd, and on boards with large
> * amounts of RAM we must avoid the initrd being so far up in RAM
> * that it is outside lowmem and inaccessible to the kernel.
> * So for boards with less than 256MB of RAM we put the initrd
> * halfway into RAM, and for boards with 256MB of RAM or more we put
> * the initrd at 128MB.
> * We also refuse to put the initrd somewhere that will definitely
> * overlay the kernel we just loaded, though for kernel formats which
> * don't tell us their exact size (eg self-decompressing 32-bit kernels)
> * we might still make a bad choice here.
> */
>
I think this lowmem does not mean below 4GB. and it is to make sure
the initrd_start > memblock_start_of_DRAM for Linux address range check.
> Is this just because the base RAM address of the board is outside of the
> 32 bit address range?
Yes, it is.
--
BRs
Schspa Shi
