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. Thomas