Re: [PATCH kvmtool 2/6] disk/core: Do not modify const strings in disk_img_name_parser()

[Alexandru Elisei <alexandru.elisei@arm.com>]

Hi Will,

On Sun, May 17, 2026 at 09:29:23AM +0100, Will Deacon wrote:
> On Mon, Mar 23, 2026 at 03:02:17PM +0000, Alexandru Elisei wrote:
> > @arg is const char *, but disk_img_name_parser() modifies it, which leads
> > to a compilation error on x86 with gcc 15.2.1:
> > 
> > disk/core.c:27:21: error: assignment discards ‘const’ qualifier from pointer target type [-Werror=discarded-qualifiers]
> >    27 |                 sep = strstr(arg, ":");
> > 
> > Make a copy of @arg and modify it instead, and be very careful to free it
> > when no longer needed.
> > 
> > Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
> > ---
> > 
> > I followed the instruction from Documentation/io-testing, but I couldn't
> > get a virtio SCSI disk work in a VM, I kept getting this kvmtool error when
> > the guest tried to use it:
> > 
> > [    0.154837] virtio_scsi virtio1: 1/0/0 default/read/poll queues
> > [    0.156965] scsi host0: Virtio SCSI HBA
> >   Fatal: VHOST_SCSI_SET_ENDPOINT failed 19
> 
> That's -ENODEV, so presumably vhost_scsi_set_endpoint() (in the host
> kernel) is failing to match the device. Can you stick some tracing in
> there to figure out what's going wrong?

I am pretty sure I made a configuration error when creating the scsi-disk in
userspace. Jean-Philippe was able to run upstream kvmtool (without this series)
with a scsi-disk with his setup. I'll try harder for the next iteration.

Thanks,
Alex