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Re: [Qemu-devel] [PATCH] BCM2837 and machine raspi3

From: BALATON Zoltan
Subject: Re: [Qemu-devel] [PATCH] BCM2837 and machine raspi3
Date: Mon, 22 Jan 2018 12:41:41 +0100 (CET)
User-agent: Alpine 2.21 (BSF 202 2017-01-01)


On Thu, 18 Jan 2018, bzt bzt wrote:
Since you still haven't merged Alistair's patch, I decided to include it in
my own.

Which patch exactly are you referring to? Please be patient and don't get upset. Merging a patch can take some time, especially if code freeze and holiday season are in the middle and some backlog is accumulated. I suggest to follow instructions described here:


and send this version as a new message with proper format and commit message so it can be easily found and tested by relevant people and don't give up if they are busy and can't reply immediately. Just politely remind them after a week or two as suggested on the above wiki page.

Rationale for the above: Replying to an older thread may not show up at the end if someone uses threaded view but gets burried in some old thread so new patches should be new top level threads, only replies to the same patch or series should be sent as replies. Also your patch has been mangled by the email client and some lines are broken. This is a problem because it cannot be tested by using git am so it's more difficult to check. Please make sure you send it unflowed so the patch is not changed by the client (or use git send-email).

All in all, I think your work is interesting and the lack of reply only means that people who could review and merge it were too busy not lack of interest so keep up improving the patch and don't give up.


I've shrinked the number of modified files to two, that's the bare minimum
to support "-M raspi3" switch. Bcm2836.c modified minimally, the rest is in
raspi.c. I've renamed raspi2_init() to raspi_init() 'cos now it initializes
raspi3 as well, no additional function.

diff --git a/hw/arm/bcm2836.c b/hw/arm/bcm2836.c
index 8c43291112..5119e00051 100644
--- a/hw/arm/bcm2836.c
+++ b/hw/arm/bcm2836.c
@@ -15,6 +15,7 @@
#include "hw/arm/bcm2836.h"
#include "hw/arm/raspi_platform.h"
#include "hw/sysbus.h"
+#include "hw/boards.h"
#include "exec/address-spaces.h"

/* Peripheral base address seen by the CPU */
@@ -30,7 +31,7 @@ static void bcm2836_init(Object *obj)

    for (n = 0; n < BCM2836_NCPUS; n++) {
        object_initialize(&s->cpus[n], sizeof(s->cpus[n]),
-                          "cortex-a15-" TYPE_ARM_CPU);
+                          current_machine->cpu_type);
        object_property_add_child(obj, "cpu[*]", OBJECT(&s->cpus[n]),
diff --git a/hw/arm/raspi.c b/hw/arm/raspi.c
index cd5fa8c3dc..24a9243440 100644
--- a/hw/arm/raspi.c
+++ b/hw/arm/raspi.c
@@ -5,6 +5,8 @@
 * Rasperry Pi 2 emulation Copyright (c) 2015, Microsoft
 * Written by Andrew Baumann
+ * Raspberry Pi 3 emulation Copyright (c) 2018 by bzt
+ *
 * This code is licensed under the GNU GPLv2 and later.

@@ -22,10 +24,11 @@
#define SMPBOOT_ADDR    0x300 /* this should leave enough space for ATAGS
#define MVBAR_ADDR      0x400 /* secure vectors */
#define BOARDSETUP_ADDR (MVBAR_ADDR + 0x20) /* board setup code */
-#define FIRMWARE_ADDR   0x8000 /* Pi loads kernel.img here by default */
+#define FIRMWARE_ADDR_2    0x8000 /* Pi 2 loads kernel.img here by default
+#define FIRMWARE_ADDR_3   0x80000 /* Pi 3 loads kernel8.img here by
default */

/* Table of Linux board IDs for different Pi versions */
-static const int raspi_boardid[] = {[1] = 0xc42, [2] = 0xc43};
+static const int raspi_boardid[] = {[1] = 0xc42, [2] = 0xc43, [3] = 0xc44};

typedef struct RasPiState {
    BCM2836State soc;
@@ -83,8 +86,8 @@ static void setup_boot(MachineState *machine, int
version, size_t ram_size)
    binfo.secure_board_setup = true;
    binfo.secure_boot = true;

-    /* Pi2 requires SMP setup */
-    if (version == 2) {
+    /* Pi2 and Pi3 requires SMP setup */
+    if (version >= 2) {
        binfo.smp_loader_start = SMPBOOT_ADDR;
        binfo.write_secondary_boot = write_smpboot;
        binfo.secondary_cpu_reset_hook = reset_secondary;
@@ -94,15 +97,15 @@ static void setup_boot(MachineState *machine, int
version, size_t ram_size)
     * the normal Linux boot process
    if (machine->firmware) {
+        binfo.entry = version==3? FIRMWARE_ADDR_3 : FIRMWARE_ADDR_2;
        /* load the firmware image (typically kernel.img) */
-        r = load_image_targphys(machine->firmware, FIRMWARE_ADDR,
-                                ram_size - FIRMWARE_ADDR);
+        r = load_image_targphys(machine->firmware, binfo.entry,
+                                ram_size - binfo.entry);
        if (r < 0) {
            error_report("Failed to load firmware from %s",

-        binfo.entry = FIRMWARE_ADDR;
        binfo.firmware_loaded = true;
    } else {
        binfo.kernel_filename = machine->kernel_filename;
@@ -113,7 +116,7 @@ static void setup_boot(MachineState *machine, int
version, size_t ram_size)
    arm_load_kernel(ARM_CPU(first_cpu), &binfo);

-static void raspi2_init(MachineState *machine)
+static void raspi_init(MachineState *machine)
    RasPiState *s = g_new0(RasPiState, 1);
    uint32_t vcram_size;
@@ -121,6 +124,7 @@ static void raspi2_init(MachineState *machine)
    BlockBackend *blk;
    BusState *bus;
    DeviceState *carddev;
+    int version = machine->cpu_type==ARM_CPU_TYPE_NAME("cortex-a15")? 2 :

    object_initialize(&s->soc, sizeof(s->soc), TYPE_BCM2836);
    object_property_add_child(OBJECT(machine), "soc", OBJECT(&s->soc),
@@ -137,8 +141,8 @@ static void raspi2_init(MachineState *machine)
    object_property_set_int(OBJECT(&s->soc), smp_cpus, "enabled-cpus",
-    object_property_set_int(OBJECT(&s->soc), 0xa21041, "board-rev",
-                            &error_abort);
+    object_property_set_int(OBJECT(&s->soc), version==3 ? 0xa02082 :
+                            "board-rev", &error_abort);
    object_property_set_bool(OBJECT(&s->soc), true, "realized",

    /* Create and plug in the SD cards */
@@ -155,21 +159,39 @@ static void raspi2_init(MachineState *machine)

    vcram_size = object_property_get_uint(OBJECT(&s->soc), "vcram-size",
-    setup_boot(machine, 2, machine->ram_size - vcram_size);
+    setup_boot(machine, version, machine->ram_size - vcram_size);

static void raspi2_machine_init(MachineClass *mc)
    mc->desc = "Raspberry Pi 2";
-    mc->init = raspi2_init;
+    mc->init = raspi_init;
    mc->block_default_type = IF_SD;
    mc->no_parallel = 1;
    mc->no_floppy = 1;
    mc->no_cdrom = 1;
    mc->max_cpus = BCM2836_NCPUS;
    mc->min_cpus = BCM2836_NCPUS;
    mc->default_cpus = BCM2836_NCPUS;
+    mc->default_cpu_type = ARM_CPU_TYPE_NAME("cortex-a15");
    mc->default_ram_size = 1024 * 1024 * 1024;
    mc->ignore_memory_transaction_failures = true;
DEFINE_MACHINE("raspi2", raspi2_machine_init)
+static void raspi3_machine_init(MachineClass *mc)
+    mc->desc = "Raspberry Pi 3";
+    mc->init = raspi_init;
+    mc->block_default_type = IF_SD;
+    mc->no_parallel = 1;
+    mc->no_floppy = 1;
+    mc->no_cdrom = 1;
+    mc->max_cpus = BCM2836_NCPUS;
+    mc->min_cpus = BCM2836_NCPUS;
+    mc->default_cpus = BCM2836_NCPUS;
+    mc->default_cpu_type = ARM_CPU_TYPE_NAME("cortex-a53");
+    mc->default_ram_size = 1024 * 1024 * 1024;
+    mc->ignore_memory_transaction_failures = true;
+DEFINE_MACHINE("raspi3", raspi3_machine_init)

Hope it's simple enough to be reviewed easily, and it uses CPU type strings
as requested.


On Wed, Nov 29, 2017 at 8:52 AM, bzt bzt <address@hidden> wrote:

On Tue, Nov 28, 2017 at 6:54 PM, Andrew Baumann <
address@hidden> wrote:

From: bzt bzt [mailto:address@hidden
Sent: Tuesday, 28 November 2017 03:27

Yes, I agree. I've provided a parameterised version on Oct 24, which
does not
have a separate bcm2837 implementation. Is that patch ok?

That patch was moving in the right direction, but I think there were two
problems with it. First, the right way to pass a parameter is via a
property field (as Peter explained). Second, IMO the parameter should be
the CPU model string to instantiate and not the Pi version number.


Or should I wait
for Alistair's patch (https://lists.gnu.org/archive

Alistair's patch doesn't actually help you as far as I can see, since it
doesn't change what CPU bcm2836 instantiates. I think it just means that if
the user specifies a different CPU type they get an error rather than being
silently ignored.

It does add the CPU model string, which can and should be used in bcm2836
to decide which CPU to instatiate (regardless the method of passing that
parameter). If I add yet another CPU model string, the two patch will be in
conflict containing redundant information. Also I'm sure would raspi3 use
different cpus, we should always instantiate the one the user specified.
Although here is only one possible CPU model, still that seems to be the
correct behavior. Don't get me wrong, I don't criticize, I just want to
find the best solution. Setting the CPU model only once for each version
seems right. I was thinking: if there's going to be a user specified CPU
model string anyway, why not use that one?



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