[PATCH] arm: bootm: Disable LMB reservation for command line and board info on arm64

[Jan Kiszka]

On 21.07.21 01:34, Marek Vasut wrote:
> On 7/20/21 11:08 AM, Jan Kiszka wrote:
> [...]
>>> diff --git a/arch/arm/lib/bootm.c b/arch/arm/lib/bootm.c
>>> index f60ee3a7e6..23b99a541c 100644
>>> --- a/arch/arm/lib/bootm.c
>>> +++ b/arch/arm/lib/bootm.c
>>> @@ -43,6 +43,7 @@ DECLARE_GLOBAL_DATA_PTR;
>>>     static struct tag *params;
>>>   +#ifndef CONFIG_ARM64
>>>   static ulong get_sp(void)
>>>   {
>>>       ulong ret;
>>> @@ -86,6 +87,7 @@ void arch_lmb_reserve(struct lmb *lmb)
>>>           break;
>>>       }
>>>   }
>>> +#endif
>>>     __weak void board_quiesce_devices(void)
>>>   {
>>>
>> This causes troubles for [1], but I have no clue yet, what is happening.
>> Without the patch, we start like this:
>>
>> Found U-Boot script /boot/boot.scr
>> 889 bytes read in 21 ms (41 KiB/s)
>> ## Executing script at 83000000
>> Loading /usr/lib/linux-image-4.19.94/ti/k3-am6548-iot2050-advanced.dtb...
>> 78306 bytes read in 25 ms (3 MiB/s)
>> Loading /boot/vmlinux-4.19.94...
>> 13537288 bytes read in 107 ms (120.7 MiB/s)
>> ## Flattened Device Tree blob at 82000000
>>     Booting using the fdt blob at 0x82000000
>>     Loading Device Tree to 00000000fdefa000, end 00000000fdf101e1 ... OK
>>
>> Starting kernel ...
>>
>>
>> With the patch applied, I'm getting stuck like this:
>>
>> Found U-Boot script /boot/boot.scr
>> 889 bytes read in 21 ms (41 KiB/s)
>> ## Executing script at 83000000
>> Loading /usr/lib/linux-image-4.19.94/ti/k3-am6548-iot2050-advanced.dtb...
>> 78306 bytes read in 25 ms (3 MiB/s)
>> Loading /boot/vmlinux-4.19.94...
>> 13537288 bytes read in 109 ms (118.4 MiB/s)
>> ## Flattened Device Tree blob at 82000000
>>     Booting using the fdt blob at 0x82000000
>>     Loading Device Tree to 00000000fffe9000, end 00000000fffff1e1 ...
>>
>>
>> Obviously, the DT target adress changed, possibly to an
>> unsupported/reserved address. But I do not understand the mechanics
>> behind all this yet. Any hints welcome on what goes wrong here and
>> whether something needs to be adjusted in our board settings.
> 
> Can you share the output of bdinfo on this board ?

Sure (with your commit reverted for now):

IOT2050> bdinfo
boot_params = 0x0000000000000000
DRAM bank   = 0x0000000000000000
-> start    = 0x0000000080000000
-> size     = 0x0000000080000000
flashstart  = 0x0000000000000000
flashsize   = 0x0000000000000000
flashoffset = 0x0000000000000000
baudrate    = 115200 bps
relocaddr   = 0x00000000fff2d000
reloc off   = 0x000000007f72d000
Build       = 64-bit
current eth = unknown
ethaddr     = 70:77:77:77:57:70
IP addr     = <NULL>
fdt_blob    = 0x00000000fdef9f10
new_fdt     = 0x00000000fdef9f10
fdt_size    = 0x0000000000012ea0
lmb_dump_all:
 memory.cnt  = 0x1
 memory[0]      [0x80000000-0xffffffff], 0x80000000 bytes flags: 0
 reserved.cnt  = 0x2
 reserved[0]    [0x9e800000-0xa21fffff], 0x03a00000 bytes flags: 4
 reserved[1]    [0xfdef86c0-0xffffffff], 0x02107940 bytes flags: 0
arch_number = 0x0000000000000000
TLB addr    = 0x00000000ffff0000
irq_sp      = 0x00000000fdef9b20
sp start    = 0x00000000fdef9b20
Early malloc usage: 23c8 / 8000


There is some "TLB" block apparently overlapping when we move the DT.
What's this? Looking at the code, not a TLB with the usual meaning but
rather the page table U-Boot uses for itself, right?

Were we just lucky so far with side effects of the LMB reservation on
this platform (and I suspect that it affect k3 in general, not only our
board)?

Thanks,
Jan

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