From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44118) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fXMVb-0006oE-Sn for qemu-devel@nongnu.org; Mon, 25 Jun 2018 04:06:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fXMVW-0002Bu-VT for qemu-devel@nongnu.org; Mon, 25 Jun 2018 04:05:59 -0400 Date: Mon, 25 Jun 2018 10:05:48 +0200 From: Cornelia Huck Message-ID: <20180625100548.64222dad.cohuck@redhat.com> In-Reply-To: <88d9afed-f91d-c320-13c8-9a93fc52b700@de.ibm.com> References: <20180622194736.GA5794@roeck-us.net> <126ac556-0602-b927-58f5-cb5f65a5e0ec@de.ibm.com> <88d9afed-f91d-c320-13c8-9a93fc52b700@de.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] s390 qemu boot failure in -next List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Christian Borntraeger Cc: Guenter Roeck , Martin Schwidefsky , Vasily Gorbik , Heiko Carstens , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, qemu-s390x , qemu-devel , Thomas Huth On Mon, 25 Jun 2018 09:27:59 +0200 Christian Borntraeger wrote: > Also adding QEMU. > > On 06/25/2018 09:10 AM, Christian Borntraeger wrote: > > > > > > On 06/22/2018 09:47 PM, Guenter Roeck wrote: > >> Hi, > >> > >> starting with commit 's390/boot: make head.S and als.c be part of the > >> decompressor only' in -next, s390 immages no longer boot in qemu. > >> As far as I can see, the reason is that the command line is no longer > >> passed from qemu to the kernel, which results in a panic because the > >> root file system can not be mounted. > >> > >> Was this change made on purpose ? If so, is there a way to get qemu > >> back to working ? > > > > Certainly not on purpose. > > > > Vasily, I can reproduce this with KVM and an external kernel boot of the vmlinux file (the elf file) > > > > e.g. > > > > qemu-system-s390 -enable-kvm -nographic -kernel vmlinux -append "this string no longer is command line" > > > > The compressed image (bzImage) seems to work fine though. > > > > This seems to be an unfortunate side effect of QEMUs ways to "guess" its Linux (checking for start > > address 0x10000, which is no longer true for the vmlinux file). With the pure vmlinux elf file > > the load address is 0x100000 as there is no unpacker. Do we consider these locations to be an exported interface, or is it just QEMU guessing? > > > > Guenter, can you check if arch/s390/boot/bzImage works for you as a workaround? > > Something like this in QEMU > > diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c > index f278036fa7..14153ce880 100644 > --- a/hw/s390x/ipl.c > +++ b/hw/s390x/ipl.c > @@ -187,11 +187,13 @@ static void s390_ipl_realize(DeviceState *dev, Error **errp) > */ > if (pentry == KERN_IMAGE_START || pentry == 0x800) { > ipl->start_addr = KERN_IMAGE_START; > - /* Overwrite parameters in the kernel image, which are "rom" */ > - strcpy(rom_ptr(KERN_PARM_AREA), ipl->cmdline); > } else { > ipl->start_addr = pentry; > } > + if (ipl->cmdline) { > + /* If there is a command line, put it in the right place */ > + strcpy(rom_ptr(KERN_PARM_AREA), ipl->cmdline); > + } Check for the magic Linux string (like in the non-elf case) first? > > if (ipl->initrd) { > ram_addr_t initrd_offset; > > would put the command line in no matter what the start address is. I'm for putting that one in (and backporting it to qemu-stable). It's a bit worrying, though, that our ipl code is so fragile...