RE: [Xen-ia64-devel] Problem with xen-unstable cset 7937 (grant tabletransfer fix)

["Magenheimer, Dan (HP Labs Fort Collins)" <dan.magenheimer@xxxxxx>]

Well there's a lot of individual pieces and I may have
missed something but I was able to boot domU with xen-ia64
tip but when I applied only the grant_table changes (including
on the xenlinux side) domU didn't boot -- Cannot open root
device.

> -----Original Message-----
> From: Magenheimer, Dan (HP Labs Fort Collins) 
> Sent: Wednesday, November 23, 2005 4:09 PM
> To: 'Keir Fraser'
> Cc: 'xen-ia64-devel@xxxxxxxxxxxxxxxxxxx'
> Subject: RE: [Xen-ia64-devel] Problem with xen-unstable cset 
> 7937 (grant tabletransfer fix)
> 
> Thanks very much!
> 
> There is a typo in gnttab_shared_mfn in the asm-ia64/grant_table.h
> you created ((t)shared should be (t)->shared) and I found a
> misspelling in include/asm-ia64/mm.h (PGT_writeable should
> be PGT_writable... this is never actually used on ia64 but
> needs to be defined syntactically to compile).  With these
> fixes, it compiles.
> 
> However, it doesn't run... booting domU gets "Cannot open
> root device".  I will repeat the experiment with xen-ia64 tip
> (to verify somethin else isn't screwed up) and then with
> xen-ia64 tip with just the grant_table changes to see if
> that works.
> 
> Or did I miss something that you had left for me to fix
> semantically in the new ia64-specific header file?
> 
> Thanks,
> Dan
> 
> 
> > -----Original Message-----
> > From: Magenheimer, Dan (HP Labs Fort Collins) 
> > Sent: Tuesday, November 22, 2005 9:39 AM
> > To: 'Keir Fraser'
> > Cc: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> > Subject: RE: [Xen-ia64-devel] Problem with xen-unstable cset 
> > 7937 (grant tabletransfer fix)
> > 
> > > However, I see no need to ifdef the code that uses pfn_valid, 
> > > get_page[_type] and put_page[_type]. They are easily 
> > noop'ed if they 
> > > mean nothing on ia64 (in fact I notice that you already 
> > > define them). I 
> > > would imagine that at least pfn_valid() makes sense though?
> > 
> > True, I think I can get around these easily enough.  One could
> > reasonably argue that the whole concept of page type is very 
> > x86-specific
> > but since it can be easily overridden, we can skip dealing 
> > with it now.
> > 
> > > Apart from that, I also didn't understand the changes in 
> the block 
> > > commented 'fundamental difference here'.
> > 
> > "Fundamental" is overstated I guess.  What I meant is that 
> the control
> > flow and the fact that the code block is completely different 
> > depending
> > on whether dom0 or domU would make it hard to hide the ia64-specific
> > implementation behind the existing code, so some separate
> > arch_grant_setup_table may be necessary.
> > 
> > > But looks to me like we ought to be able to move ia64 onto common 
> > > grant_table.c implementation fairly easily. We should shoot 
> > > down a few 
> > > of the easy ifdefs first though.
> > 
> > OK, if you could:
> > - create an asm/grant_table.h and put ORDER_GRANT_FRAMES in it
> > - move the big block in _gnttab_map_grant_ref (doing things
> >   with l1_pgentry etc) into arch_gnttab_map_grant_ref (or some
> >   other way out of grant_table.c) so that I can no-op it
> > - replace the "fundamental" block in grant_setup_table with
> >   a function call -- arch_grant_setup_table(d,op,uop)?? --
> >   this probably becomes a static inline in asm/grant_table.h
> > - replace the asm statement with a function call that I can
> >   define differently for ia64
> > then I think I can handle the rest and all the ifdef's will
> > be gone too.
> > 
> > Thanks,
> > Dan
> > 
> 

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