Re: [PATCH v5 05/12] pc-bios: s390x: Remove unneeded dasd-ipl.c reset psw mask changes

[Thomas Huth <thuth@redhat.com>]

On 25/06/2020 12.57, Thomas Huth wrote:
> On 24/06/2020 09.52, Janosch Frank wrote:
>> jump_to_low_kernel() and the functions that it calls will already or
>> 64 bit addressing into the reset psw mask when executing
>> jump_to_IPL_2() after the diag308 subcode 1.
> 
> Hmm, the jump_to_IPL_code() also sets the 64-bit addressing bits ... but 
> jump_to_low_kernel() has some logic that tests for the bits before that 
> function is called:
> 
>      /* Trying to get PSW at zero address */
>      if (*((uint64_t *)0) & RESET_PSW_MASK) {
>          jump_to_IPL_code((*((uint64_t *)0)) & 0x7fffffff);
>      }
> 
> Could it be that the code in dasd-ipl.c has been written with that 
> if-statement in mind?

... in that case, the code in dasd-ipl.c should maybe rather call 
jump_to_IPL_code((*((uint64_t *)0)) & 0x7fffffff) directly instead of 
going through jump_to_low_kernel(), I guess.

Jason, do you remember the intention here?

  Thomas