[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [Bug 1826827] Re: dtc crash; pnv_dt_serial cannot find lpc'
From: |
David Gibson |
Subject: |
[Qemu-devel] [Bug 1826827] Re: dtc crash; pnv_dt_serial cannot find lpc's phandle |
Date: |
Mon, 06 May 2019 06:37:52 -0000 |
IIUC there are two bugs here
1) The powernv machine in qemu is attempting to use a phandle for node
that doesn't have one. It will need to assign a phandle to that node
and re-use it elsewhere. This should be pretty straightforward.
2) dtc is crashing with an assertion - that shouldn't happen, even on
bad input it should error out rather than crashing. The problem also
occurs with current upstream dtc - I'll try to investigate this.
Btw, I'm assuming where you say 'dtc -O dtb -I dts -o out.dts dtb' you actually
meant 'dtc -I dtb -O dts -o out.dts dtb' (i.e. -I and -O swapped around),
since you're trying to decompile a blob to source rather than the other way
around.
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1826827
Title:
dtc crash; pnv_dt_serial cannot find lpc's phandle
Status in QEMU:
New
Bug description:
Qemu version:
QEMU emulator version 4.0.50 (v4.0.0-142-ge0fb2c3d89)
Copyright (c) 2003-2019 Fabrice Bellard and the QEMU Project developers
dtc version:
Version: DTC 1.5.0-g5c3513f6
-------------------------------------------------------------------------
pnv_dt_serial has a line which is supposed to set the interrupt-parent of the
"address@hidden" node to the phandle of "address@hidden".
To that end, it calls fdt_get_phandle as shown below:
_FDT((fdt_setprop_cell(fdt, node, "interrupt-parent", fdt_get_phandle(fdt,
lpc_off))));
The function fdt_get_phandle fails to find the property "phandle" (or
"linux,phandle") for the lpc node. Consequently, pnv_dt_serial sets
the interrupt-parent to 0.
Now boot the qemu-system-ppc64 powernv machine, and extract the fdt by
using the qemu monitor's pmemsave command, taking help of the OPAL
firmware's messages to locate the fdt in the physical ram.
qemu-system-ppc64 -m 1g -machine powernv,num-chips=1 \
-cpu power9 -smp 2,cores=2,threads=1 -accel tcg,thread=multi \
-kernel ./vmlinux \
-append 'disable_radix' \
-serial mon:stdio -nographic -nodefaults
The kernel vmlinux contains nothing but a single instruction which
loops infintely, so that we can gather OPAL's messages, especially the
one below:
[ 0.168845963,5] INIT: Starting kernel at 0x20000000, fdt at
0x304b0b70 14404 bytes
Once the fdt is dumped to a file, run the following:
'dtc -O dtb -I dts -o out.dts dtb'
After a few warnings, the dtc application crashes because an assertion
was fired.
out.dts: Warning (unit_address_vs_reg): /address@hidden/address@hidden: node
has a unit name, but no reg property
out.dts: Warning (simple_bus_reg): /address@hidden/address@hidden: missing or
empty reg/ranges property
out.dts: Warning (avoid_unnecessary_addr_size): /ibm,opal: unnecessary
#address-cells/#size-cells without "ranges" or child "reg" property
out.dts: Warning (unique_unit_address): /address@hidden: duplicate
unit-address (also used in node /address@hidden)
out.dts: Warning (chosen_node_stdout_path): /chosen:linux,stdout-path: Use
'stdout-path' instead
dtc: livetree.c:575: get_node_by_phandle: Assertion `generate_fixups' failed.
Aborted (core dumped)
The assertion is fired because get_node_by_phandle receives a phandle
value of 0, which is unexpected, unless fixups are needed (They are
not, when running the dtc command).
Back inside pnv_dt_serial, if the line that sets "interrupt-parent"
for the serial device node is commented out, the dtc crash is
prevented. Looking at hw/ppc/e500.c, it takes care of allocating
necessary phandle values in the nodes, so a similar method can be
adopted for powernv.
The dtb is attached.
Edit: Add version, Correct filenames.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1826827/+subscriptions
- [Qemu-devel] [Bug 1826827] Re: dtc crash; pnv_dt_serial cannot find lpc's phandle,
David Gibson <=