ARM: pxa/corgi: armv5te kernel 4.12 fails to decompress compiled with gcc7

[Petr Cvek]

Dne 17.10.2017 v 10:18 Andrea Adami napsal(a):
> On Tue, Oct 17, 2017 at 10:10 AM, Petr Cvek <petrcvekcz at gmail.com> wrote:
>> Dne 17.10.2017 v 10:02 Andrea Adami napsal(a):
>>>
>>> <cut>
>>>
>>> Hi,
>>
>> Hi
>>
>>
>>>
>>> I am trying to debug further but I don't have any output on serial
>>> console...
>>> I enabled:
>>>
>>> CONFIG_DEBUG_LL=y
>>> CONFIG_DEBUG_PXA_UART1=y
>>> # CONFIG_DEBUG_ICEDCC is not set
>>> # CONFIG_DEBUG_SEMIHOSTING is not set
>>> # CONFIG_DEBUG_LL_UART_8250 is not set
>>> # CONFIG_DEBUG_LL_UART_PL01X is not set
>>> CONFIG_DEBUG_LL_INCLUDE="debug/8250.S"
>>> CONFIG_DEBUG_UART_8250=y
>>> CONFIG_DEBUG_UART_PHYS=0x40100000
>>> CONFIG_DEBUG_UART_VIRT=0xf6200000
>>> CONFIG_DEBUG_UART_8250_SHIFT=2
>>> # CONFIG_DEBUG_UART_8250_WORD is not set
>>> # CONFIG_DEBUG_UART_8250_PALMCHIP is not set
>>> # CONFIG_DEBUG_UART_8250_FLOW_CONTROL is not set
>>> CONFIG_UNCOMPRESS_INCLUDE="mach/uncompress.h"
>>> CONFIG_EARLY_PRINTK=y
>>>
>>> then I added #define DEBUG  to both head.S and decompress.c under
>>> arm/boot/compressed.
>>> I added earlyprintk to the cmdline args used by the kexec bootloader but
>>> nothing
>>>
>>> That kernel does boot silently, just 'Uncompresing..' then
>>> 'XZ-compressed data is corrupt -- System halted'
>>>
>>> I do have output from the Angel bootloader at 9600 and by the kernel
>>> at 115200 so the uart is working...
>>> Any hint?
>>
>>
>> If it is a problem with gcc (as Russell said before), there is no way you
>> can fix it in the kernel. Only compiling it with an older gcc version can
>> help.
>>

BTW you could add "alignment=2" (same as /proc/cpu/alignment) in your 
kernel parameters and kernel should check it even before you boot 
userspace.

But it will be *extra* slow as there will be many exceptions in the 
kernel and an emulation of the unaligned instructions. It is not a real 
permanent fix.

It should be possible to use up to march=armv5t as I elaborated it in 
the other mail.

best regards,
Petr