Re: [Qemu-devel] [Qemu-ppc] [PATCH RFC] spapr: by-pass SLOF when -kernel is provided

[Greg Kurz <groug@kaod.org>]

On Tue, 5 Jul 2016 20:51:41 +0200
Laurent Vivier <lvivier@redhat.com> wrote:

> On 05/07/2016 20:44, Greg Kurz wrote:
> > On Tue,  5 Jul 2016 16:42:37 +0200
> > Laurent Vivier <lvivier@redhat.com> wrote:
> >   
> >> As device-tree is now fully built by QEMU, we don't need SLOF
> >> anymore if the kernel is provided on the command line.
> >>
> >> In this case, don't load SLOF and boot directly into the
> >> kernel.
> >>
> >> This saves at least 5 seconds on the boot sequence.
> >>  
> > 
> > The concept looks great so I gave a try with a fedora24 guest.  
> 
> I did the same test with a rhel7 vmlinuz adn intramfs and it works fine.
> 
> > 
> > I copied the kernel and initramfs to the host and passed the kernel arguments
> > taken from grub.
> > 
> > The kernel starts but the boot sequence stalls at:
> > 
> > [  OK  ] Reached target Basic System.
> > [  126.238400] dracut-initqueue[290]: Warning: dracut-initqueue timeout - starting timeout scripts  
> 
> It happens when the initramfs didn't have the disk driver: do you use
> the same disk controller with the "-kernel" than the one which was used
> when the initramfs has been created?
> 

Yes. The very same QEMU command line (except -kernel/-initrd/-append) works with
SLOF and fails without SLOF.

> > 
> > I also noticed this error:
> > 
> > [    0.127303] WARNING: nvram corruption detected: 0-length partition
> > [    0.127610] nvram: No room to create ibm,rtas-log partition, deleting any obsolete OS partitions...
> > [    0.128011] nvram: Failed to find or create ibm,rtas-log partition, err -28
> > [    0.128300] nvram: No room to create lnx,oops-log partition, deleting any obsolete OS partitions...
> > [    0.128701] nvram: Failed to find or create lnx,oops-log partition, err -28
> > Linux ppc6400] nvram: Failed to initialize oops partition!  
> 
> I've also that: perhaps SLOF is initializing the NVRAM when it is empty,
> and qemu doesn't?
> 
> I will check.
> 
> Thanks,
> Laurent
> 
> > 
> > Cc'ing Nikunj who has already worked on booting a guest without SLOF.
> > 
> >   
> >> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> >> ---
> >>  hw/ppc/spapr.c | 37 ++++++++++++++++++++-----------------
> >>  1 file changed, 20 insertions(+), 17 deletions(-)
> >>
> >> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> >> index 7f33a1b..bbdb21d 100644
> >> --- a/hw/ppc/spapr.c
> >> +++ b/hw/ppc/spapr.c
> >> @@ -1219,8 +1219,11 @@ static void ppc_spapr_reset(void)
> >>      first_ppc_cpu->env.gpr[3] = spapr->fdt_addr;
> >>      first_ppc_cpu->env.gpr[5] = 0;
> >>      first_cpu->halted = 0;
> >> -    first_ppc_cpu->env.nip = SPAPR_ENTRY_POINT;
> >> -
> >> +    if (machine->kernel_filename) {
> >> +        first_ppc_cpu->env.nip = KERNEL_LOAD_ADDR;
> >> +    } else {
> >> +        first_ppc_cpu->env.nip = SPAPR_ENTRY_POINT;
> >> +    }
> >>  }
> >>  
> >>  static void spapr_create_nvram(sPAPRMachineState *spapr)
> >> @@ -2023,23 +2026,23 @@ static void ppc_spapr_init(MachineState *machine)
> >>              initrd_base = 0;
> >>              initrd_size = 0;
> >>          }
> >> +    } else {
> >> +        if (bios_name == NULL) {
> >> +            bios_name = FW_FILE_NAME;
> >> +        }
> >> +        filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
> >> +        if (!filename) {
> >> +            error_report("Could not find LPAR firmware '%s'", bios_name);
> >> +            exit(1);
> >> +        }
> >> +        fw_size = load_image_targphys(filename, 0, FW_MAX_SIZE);
> >> +        if (fw_size <= 0) {
> >> +            error_report("Could not load LPAR firmware '%s'", filename);
> >> +            exit(1);
> >> +        }
> >> +        g_free(filename);
> >>      }
> >>  
> >> -    if (bios_name == NULL) {
> >> -        bios_name = FW_FILE_NAME;
> >> -    }
> >> -    filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
> >> -    if (!filename) {
> >> -        error_report("Could not find LPAR firmware '%s'", bios_name);
> >> -        exit(1);
> >> -    }
> >> -    fw_size = load_image_targphys(filename, 0, FW_MAX_SIZE);
> >> -    if (fw_size <= 0) {
> >> -        error_report("Could not load LPAR firmware '%s'", filename);
> >> -        exit(1);
> >> -    }
> >> -    g_free(filename);
> >> -
> >>      /* FIXME: Should register things through the MachineState's qdev
> >>       * interface, this is a legacy from the sPAPREnvironment structure
> >>       * which predated MachineState but had a similar function */  
> >   
>