[OpenBIOS] sbus slot probing
Mark Cave-Ayland
mark.cave-ayland at siriusit.co.uk
Fri Aug 19 22:44:05 CEST 2011
On 15/08/11 16:01, Bob Breuer wrote:
> Here's a preliminary patch for sbus slot probing.
Great work indeed :)
> This can be used for the preliminary dbri device patch, see my dbri-pre1
> branch at github: https://github.com/breuerr/qemu/tree/dbri-pre1
> That branch also has a rewritten fcode rom to avoid the use of the
> obsolete intr forth word. Use the SS-20 machine to get the dbri device.
>
> Todo:
> non-faulting reads so that an empty slot can be probed
> extend to probe other (all?) slots as well
> only add the slot E range for SS-20, but not SS-10
>
> Is there any existing code for sparc32 which does a non-faulting read? It
> looks like even cpeek doesn't try to catch any faults.
Not that I know of. It looks as if there may be some work that needs to
be done in qemu in order for this to happen as per the comment in
hw/sun4m_iommu.c:
case IOMMU_ARBEN:
// XXX implement SBus probing: fault when reading unmapped
// addresses, fault cause and address stored to MMU/IOMMU
s->regs[saddr] = (val & IOMMU_ARBEN_MASK) | IOMMU_MID;
break;
I have a feeling that qemu invokes a known trap for unmapped memory, so
it could be that given we know the SBus range we could just assume that
any traps occurring during a read to that range is a failed probe?
> Bob
>
> Index: drivers/sbus.c
> ===================================================================
> --- drivers/sbus.c (revision 1046)
> +++ drivers/sbus.c (working copy)
> @@ -451,11 +451,36 @@
> static void
> sbus_probe_slot_ss10(unsigned int slot, uint64_t base)
> {
> + ucell fcode;
> + unsigned char start;
> +
> // OpenBIOS and Qemu don't know how to do Sbus probing
> switch(slot) {
> case 2: // SUNW,tcx
> ob_tcx_init(slot, "/iommu/sbus/SUNW,tcx");
> break;
> + case 0xe: // dbri
> + fcode = ofmem_map_io(base, 0x1000);
> + // TODO: non-faulting read
> + start = *(unsigned char*)fcode;
> + if (start == 0xfd || start == 0xf1) {
See is_fcode() in libopenbios/fcode_load.c.
> + push_str("/iommu/sbus");
> + fword("select-dev");
> + fword("new-device");
> + push_str(NULL);
> + PUSH(0); // offset
> + PUSH(slot); // space
> + push_str("encode-unit");
> + fword("$call-parent");
> + fword("set-args");
> + PUSH(fcode);
> + PUSH(1);
> + fword("byte-load");
> + fword("finish-device");
> + fword("unselect-dev");
> + }
> + ofmem_unmap(fcode, 0x1000);
> + break;
> case 0xf: // le, esp, bpp, power-management
> ob_macio_init(slot, base, 0);
> // Power management (APC) XXX should not exist
> @@ -534,6 +559,7 @@
> { 1, 0, 0xe10000000ULL, 0x10000000,},
> { 2, 0, 0xe20000000ULL, 0x10000000,},
> { 3, 0, 0xe30000000ULL, 0x10000000,},
> + [0xe] = { 0xe, 0, 0xee0000000ULL, 0x10000000,},
> [0xf] = { 0xf, 0, 0xef0000000ULL, 0x10000000,},
> };
The only other thing I'd like to see, as you mention, is the probe moved
into a separate function which can be called from the appropriate
_init() functions. I'd be interested to follow the discussion related to
handling the various traps that occur during a fault access on this
thread as you progress.
ATB,
Mark.
--
Mark Cave-Ayland - Senior Technical Architect
PostgreSQL - PostGIS
Sirius Corporation plc - control through freedom
http://www.siriusit.co.uk
t: +44 870 608 0063
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