On 25.04.2018 18:03, Christian Borntraeger wrote: > > > On 04/25/2018 05:36 PM, Thomas Huth wrote: >> On 25.04.2018 14:44, Christian Borntraeger wrote: >>> >>> >>> On 04/25/2018 02:41 PM, Christian Borntraeger wrote: >>>> You load from address 0. >>>> >>>> On 04/25/2018 02:34 PM, Thomas Huth wrote: >>>>> On 25.04.2018 14:18, Christian Borntraeger wrote: >>>>>> >>>>>> On 04/25/2018 11:08 AM, Thomas Huth wrote: >>>>>> >>>>>>> --- a/pc-bios/s390-ccw/netmain.c >>>>>>> +++ b/pc-bios/s390-ccw/netmain.c >>>>>>> @@ -283,6 +283,15 @@ void panic(const char *string) >>>>>>> } >>>>>>> } >>>>>>> >>>>>>> +void write_subsystem_identification(void) >>>>>>> +{ >>>>>>> + uint32_t *schid = (uint32_t *) 184; >>>>>>> + uint32_t *zeroes = (uint32_t *) 188; >>>>>>> + >>>>>>> + *schid = 0; /* We must not set this for virtio-net */ >>>>>>> + *zeroes = 0; >>>>>>> +} >>>>>>> + >>>>>> >>>>>> I think we actually want to have the CCW devno of that network device >>>>>> stored. It has some value to know which CCW device we bootet from, no? >>>>> >>>>> Actually, I tried that first (and it took quite some time to debug it), >>>>> but the Linux kernel then bails out quite early, without any error >>>>> message. The trace looks like this: >>>>> >>>>> 0x0000000007801802: diag %r1,%r1,776 >>>>> 0x0000000007801780: larl %r2,0x7831004 >>>>> 0x0000000007801786: llgf %r1,8 >>>>> 0x000000000780178c: mvc 0(12,%r0),0(%r2) >>>>> 0x0000000007801792: br %r1 >>>>> 0x0000000000000418: bas %r14,512 >>>>> 0x0000000000000200: mvi 163,1 >>>>> 0x0000000000000204: slr %r0,%r0 >>>>> 0x0000000000000206: lhi %r1,2 >>>>> 0x000000000000020a: sigp %r1,%r0,18 >>>>> 0x000000000000020e: bras %r13,0x252 >>>>> 0x0000000000000252: lmh %r0,%r15,0(%r13) >>>>> 0x0000000000000258: sam31 >>>>> 0x000000000000025a: br %r14 >>>>> 0x000000000000041c: lh %r1,184 >>>>> 0x0000000000000420: bct %r1,1322 >>>>> 0x0000000000000424: l %r1,184 >>>>> 0x0000000000000428: la %r2,1840 >>>>> 0x000000000000042c: bas %r14,640 >>>>> 0x0000000000000280: la %r4,0(%r14) >>>>> 0x0000000000000284: la %r3,792 >>>>> 0x0000000000000288: la %r5,804 >>>>> 0x000000000000028c: la %r6,888 >>>>> 0x0000000000000290: la %r7,20 >>>>> 0x0000000000000294: st %r2,4(%r6) >>>>> 0x0000000000000298: la %r2,80(%r2) >>>>> 0x000000000000029c: la %r6,8(%r6) >>>>> 0x00000000000002a0: bct %r7,660 >>>>> 0x00000000000002a4: lctl %c6,%c6,868 >>>>> 0x00000000000002a8: slr %r2,%r2 >>>>> 0x00000000000002aa: ssch 0(%r3) >>>>> 0x00000000000002ae: bne 786 >>>>> 0x0000000000000312: lpsw 880 >>>>> Guest crashed on cpu 0: disabled-wait >>>>> PSW: 0x000a000000000000 0x0000000000000000 >>>>> >>>>> That's the Lloader function in arch/s390/kernel/head.S which is failing >>>>> here, so seems like Linux tries to load from a block device in case >>>>> there is a value in 184. Thus I assume that 184 has to contain 0 in this >>>>> case. >>>> >>>> Hmm, I think this is because we jump to 418 for your kernel (which is the >>>> loader >>>> that tries to bootstrap the ccw ipl). When you look at ipl.c we override >>>> that >>>> and jump to 0x10000 instead for linux (which is also hackish) for image >>>> files. >>>> So I guess if we would do a psw restart instead (like you do) on a kernel >>>> image >>>> the normal ipl would also fail.... >>> >>> FWIW, zipl also loads linux kernels from 0x10000 >> >> OK, I just checked, and indeed, if I change to code to jump to 0x10000, >> it also works when setting a value into 184. So I'll change this patch >> here accordingly. > > This will of course break loading non-Linux binaries. > Could we maybe check 0x10008 for S390EP (see head.S) which indicates Linux > since 3.2 or so > and only in that case change the address to 0x10000?
Sounds like a good idea! I assume load_iso_bc_entry() in bootmap.c should use that mechanism, too? And what about hw/s390/ipl.c, should we change the code there, too? Thomas