On 04.12.18 15:06, David Hildenbrand wrote: > On 04.12.18 14:58, Janosch Frank wrote: >> On 04.12.18 14:52, David Hildenbrand wrote: >>> On 04.12.18 14:48, Janosch Frank wrote: >>>> Currently tests are run with the --kernel option of Qemu, which will >>>> load the ELF file and jump to the start address. When booting from >>>> disk, we need to specify a start address. This is done by setting the >>>> initial short PSW at 0x0. >>>> >>>> For later compatibility with other hypervisors the short psw has 31 >>>> bit addressing specified. >>>> >>>> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx> >>>> --- >>>> s390x/cstart64.S | 9 +++++++-- >>>> s390x/flat.lds | 8 +++++++- >>>> 2 files changed, 14 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/s390x/cstart64.S b/s390x/cstart64.S >>>> index dc7ddd6..abd6b58 100644 >>>> --- a/s390x/cstart64.S >>>> +++ b/s390x/cstart64.S >>>> @@ -14,12 +14,17 @@ >>>> >>>> .section .init >>>> >>>> -/* entry point - for KVM + TCG we directly start in 64 bit mode */ >>>> +/* >>>> + * Short init between 0x10000 and 0x10480 and then jump to 0x11000. >>>> + * 0x10480 - 0x11000 are written to by bootloader. >>>> + */ >>>> .globl start >>>> start: >>>> + sam64 # Set addressing mode to 64 bit >>> >>> I guess this was supposed to go into patch #2? >> >> No, the short PSW has only BA set because we want to boot on lpar and >> zvm later on and they start with esam, not esame. >> >> So when booting from disk we need to sam64, as we'll run with 31 at this >> point in time. > > Please add that to the description (and remove it from the description > of patch #2). Thanks! > Sure, I'll also try to add some more comments to the assembly.
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