From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: Little help with Seabios PV-Drivers for XEN Date: Thu, 10 May 2012 11:57:51 -0400 Message-ID: <20120510155751.GJ6389@phenom.dumpdata.com> References: <6035A0D088A63A46850C3988ED045A4B10A95EAB@BITCOM1.int.sbss.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Daniel Castro Cc: James Harper , "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org On Sat, Apr 07, 2012 at 08:01:14PM +0900, Daniel Castro wrote: > Yes, out of sync, anyway... > = > On Fri, Mar 9, 2012 at 8:59 AM, James Harper > wrote: > >> Hello All, > >> > >> I have a little setback with the development of PV Drivers for Xen in = SeaBIOS. > >> The initialization code that runs in 32 Bit is working properly. > >> But, when the system tries to read on the disk I use the ring macros t= o get a > >> request. The macro usage looks like this: > >> struct blkif_ring * shared =3D memalign_low(4096,4096); //return > >> 0x000fd630 this above 16bit address space SHARED_RING_INIT(shared); So > >> far I have a pointer located at 0x0009a000 Under 32bit the struct is c= orrect > >> and all is working according to plan. > >> > >> But on 16bit operation read on disk I have struct blkfront_info * shar= ed_ring > >> =3D container_of(op->drive_g.info->shared)); // I get d630 I should ge= t it from > >> the correct segment, but how? > >> RING_GET_REQUEST(shared_ring); //this returns 0xffff and should be > >> something 0xa010 segment SS or something like that > > > > Just curios, does 16 bit include the required atomic instructions to ma= nipulate the 32 bit ring counters? Or are you manipulating the ring in 32 b= it mode and only accessing the requests already retrieved from the ring in = 16 bit mode? > This is my current problem, when I do > RING_GET_REQUEST(GET_GLOBAL(blk_info->private),GET_GLOBAL(blk_info->priva= te->req_prod_pvt)); > The return address is incorrect, so I guess since inside the > RING_REQUEST MACRO I make memory access I will need to rewrite the > macro to include the SeaBios macros needed to address 32bit pointers > in 16bit mode. Which is /* Direct access to individual ring elements, by index. */ #define RING_GET_REQUEST(_r, _idx) \ (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req)) ? I would try to not use macros at the start to unravel any complexity. Did GET_GLOBAL(blk_info->private) get you a valid pointer? If you do a hexdump of that area do you get what you expect? > > > >> SeaBios has some macros that convert a pointer in 32Bit to 16Bit by ch= anging > >> the segment register, yet I do not know in what segment the ring is lo= cated, > >> and the macros are not applied inside the procedure of the macro, for > >> example: > >> MAKE_FLATPTR(GET_SEG(SS),RING_GET_REQUEST(shared_ring)); > >> But this will change a 16Bit pointer of segment SS to a 32 bit segment= . There > >> is also the reverse but, again I do not know the segment in which I sh= ould > >> look for. Lastly the process inside the macro does not get this benefi= n, and I > >> do not know if the macro will work with a pointer of size 16bits. > >> > >> Any help will be GREATLY appreciated, I am almost done. > >> > > > > I'm not sure if this would be useful, but is there a way to hand over t= he ring to the OS PV drivers and avoid the teardown/setup? > This is before there is an OS. The bios handles the boot process, > right now I am trying to get the first read on the drive, the boot > sector. > > > > James > > > = > = > = > -- = > +-=3D=3D=3D=3D=3D---------------------------+ > | +---------------------------------+ | This space intentionally blank > for notetaking. > | |=A0=A0 | Daniel Castro,=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 | > | |=A0=A0 | Consultant/Programmer.| > | |=A0=A0 | U Andes=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=A0 | > +-------------------------------------+ > = > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel