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[PULL,06/44] ppc/pnv: Add a comment on the "primary-topology-index" property

Message ID 20210930054426.357344-7-david@gibson.dropbear.id.au (mailing list archive)
State New, archived
Headers show
Series [PULL,01/44] host-utils: Fix overflow detection in divu128() | expand

Commit Message

David Gibson Sept. 30, 2021, 5:43 a.m. UTC 
From: Cédric Le Goater <clg@kaod.org>

On P10, the chip id is calculated from the "Primary topology table
index". See skiboot commits for more information [1].

This information is extracted from the hdata on real systems which
QEMU needs to emulate. Add this property for all machines even if it
is only used on POWER10.

[1] https://github.com/open-power/skiboot/commit/2ce3f083f399
    https://github.com/open-power/skiboot/commit/a2d4d7f9e14a

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20210901094153.227671-4-clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/pnv_xscom.c | 4 ++++
 1 file changed, 4 insertions(+)
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Patch

diff --git a/hw/ppc/pnv_xscom.c b/hw/ppc/pnv_xscom.c
index faa488e311..9ce018dbc2 100644
--- a/hw/ppc/pnv_xscom.c
+++ b/hw/ppc/pnv_xscom.c
@@ -284,6 +284,10 @@  int pnv_dt_xscom(PnvChip *chip, void *fdt, int root_offset,
     _FDT(xscom_offset);
     g_free(name);
     _FDT((fdt_setprop_cell(fdt, xscom_offset, "ibm,chip-id", chip->chip_id)));
+    /*
+     * On P10, the xscom bus id has been deprecated and the chip id is
+     * calculated from the "Primary topology table index". See skiboot.
+     */
     _FDT((fdt_setprop_cell(fdt, xscom_offset, "ibm,primary-topology-index",
                            chip->chip_id)));
     _FDT((fdt_setprop_cell(fdt, xscom_offset, "#address-cells", 1)));