From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Castro Subject: Re: Little help with Seabios PV-Drivers for XEN Date: Sat, 7 Apr 2012 20:01:14 +0900 Message-ID: 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: In-Reply-To: <6035A0D088A63A46850C3988ED045A4B10A95EAB@BITCOM1.int.sbss.com.au> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: James Harper Cc: "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org 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 Se= aBIOS. >> 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 to = 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 cor= rect >> and all is working according to plan. >> >> But on 16bit operation read on disk I have struct blkfront_info * shared= _ring >> =3D container_of(op->drive_g.info->shared)); // I get d630 I should get = 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 mani= pulate the 32 bit ring counters? Or are you manipulating the ring in 32 bit= 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->private= ->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. > >> SeaBios has some macros that convert a pointer in 32Bit to 16Bit by chan= ging >> the segment register, yet I do not know in what segment the ring is loca= ted, >> 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 shou= ld >> look for. Lastly the process inside the macro does not get this benefin,= 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 the= 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 | +-------------------------------------+