Re: [Xen-devel] [PATCH 3/4] xen: make start_info x86 specific.

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2013-02-14 at 14:43 +0000, Jan Beulich wrote:
> >>> On 14.02.13 at 15:16, Ian Campbell <ian.campbell@xxxxxxxxxx> wrote:
> > Most of this struct is PV MMU specific and it is not used on ARM at all.
> 
> I'm not convinced this is the right move.
> 
> > --- a/xen/include/public/xen.h
> > +++ b/xen/include/public/xen.h
> > @@ -706,79 +706,6 @@ typedef struct shared_info shared_info_t;
> >   *     extended by an extra 4MB to ensure this.
> >   */
> >  
> > -#define MAX_GUEST_CMDLINE 1024
> > -struct start_info {
> > -    /* THE FOLLOWING ARE FILLED IN BOTH ON INITIAL BOOT AND ON RESUME.    
> > */
> > -    char magic[32];             /* "xen-<version>-<platform>".            
> > */
> > -    unsigned long nr_pages;     /* Total pages allocated to this domain.  
> > */
> > -    unsigned long shared_info;  /* MACHINE address of shared info struct. 
> > */
> > -    uint32_t flags;             /* SIF_xxx flags.                         
> > */
> > -    xen_pfn_t store_mfn;        /* MACHINE page number of shared page.    
> > */
> > -    uint32_t store_evtchn;      /* Event channel for store communication. 
> > */
> > -    union {
> > -        struct {
> > -            xen_pfn_t mfn;      /* MACHINE page number of console page.   
> > */
> > -            uint32_t  evtchn;   /* Event channel for console page.        
> > */
> > -        } domU;
> > -        struct {
> > -            uint32_t info_off;  /* Offset of console_info struct.         
> > */
> > -            uint32_t info_size; /* Size of console_info struct from 
> > start.*/
> > -        } dom0;
> > -    } console;
> 
> What is PV MMU related up to here?

Hrm, perhaps categorising this as PV MMU was a mistake on my part.

These are all unused on ARM in terms of the hypervisor ABI since it uses
HVM like mechanisms for those which are appropriate and doesn't use a
bunch of the others at all.

> > -struct xen_multiboot_mod_list
> > -{
> > -    /* Address of first byte of the module */
> > -    uint32_t mod_start;
> > -    /* Address of last byte of the module (inclusive) */
> > -    uint32_t mod_end;
> > -    /* Address of zero-terminated command line */
> > -    uint32_t cmdline;
> > -    /* Unused, must be zero */
> > -    uint32_t pad;
> > -};
> 
> And this one isn't either, albeit I'm not sure about its actual use.

It's unused AFAICT.

Ian.


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