Re: [qemu-s390x] [PATCH v6 06/12] s390-ccw: parse and set boot menu options

[Collin L. Walling]

On 02/16/2018 11:36 AM, Viktor Mihajlovski wrote:
> On 16.02.2018 17:20, Thomas Huth wrote:
> [...]
> > > diff --git a/hw/s390x/ipl.h b/hw/s390x/ipl.h
> > > index cab8a97..7c3cab8 100644
> > > --- a/hw/s390x/ipl.h
> > > +++ b/hw/s390x/ipl.h
> > > @@ -60,10 +60,15 @@ typedef struct IplBlockQemuScsi IplBlockQemuScsi;
> > >   
> > >   #define QIPL_ADDRESS  0xcc
> > >   
> > > +#define BOOT_MENU_FLAG_CMD_OPTS  0x80
> > > +#define BOOT_MENU_FLAG_ZIPL_OPTS 0x40
> > > +
> > >   struct QemuIplParameters {
> > > -    uint8_t  reserved1[4];
> > > +    uint8_t  boot_menu_flags;
> > > +    uint8_t  reserved1;
> > > +    uint32_t boot_menu_timeout;
> > >       uint64_t netboot_start_addr;
> > The netboot_start_addr field is now never aligned anymore, neither on
> > the host side, nor in guest memory. Not a big problem since the struct
> > is declared with "QEMU_PACKED", but still ... it's always nicer to try
> > to align fields to their natural boundaries. So maybe move
> > boot_menu_flags and reserved1 after netboot_start_addr ?
> Good catch ... we probably should document the alignment needs and state
> that the ipl parameters starts on a word boundary (and that the block
> may not be larger than 28 bytes) in a comment block.

How does this sound?

/* word aligned and cannot exceed 28 bytes */


> > > -    uint8_t  reserved2[16];
> > > +    uint8_t  reserved2[14];
> > >   } QEMU_PACKED;
> > >   typedef struct QemuIplParameters QemuIplParameters;
> >   Thomas


--
- Collin L Walling