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Re: [PATCH 03/10] mac_{old|new}world: Set default values for some local

From: BALATON Zoltan
Subject: Re: [PATCH 03/10] mac_{old|new}world: Set default values for some local variables
Date: Sun, 25 Sep 2022 11:16:40 +0200 (CEST) 
On Sun, 25 Sep 2022, Mark Cave-Ayland wrote:

On 17/09/2022 00:07, BALATON Zoltan wrote:

Some lines can be dropped making the code flow simpler and easier to
follow by setting default values at variable declaration for some
variables in both mac_oldworld.c and mac_newworld.c.

Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
---
  hw/ppc/mac_newworld.c | 28 +++++-----------------------
  hw/ppc/mac_oldworld.c | 27 +++++----------------------
  2 files changed, 10 insertions(+), 45 deletions(-)

diff --git a/hw/ppc/mac_newworld.c b/hw/ppc/mac_newworld.c
index 27e4e8d136..6bc3bd19be 100644
--- a/hw/ppc/mac_newworld.c
+++ b/hw/ppc/mac_newworld.c
@@ -111,11 +111,11 @@ static void ppc_core99_init(MachineState *machine)
      CPUPPCState *env = NULL;
      char *filename;
      IrqLines *openpic_irqs;
-    int i, j, k, ppc_boot_device, machine_arch, bios_size;
+    int i, j, k, ppc_boot_device, machine_arch, bios_size = -1;
      const char *bios_name = machine->firmware ?: PROM_FILENAME;
      MemoryRegion *bios = g_new(MemoryRegion, 1);
-    hwaddr kernel_base, initrd_base, cmdline_base = 0;
-    long kernel_size, initrd_size;
+    hwaddr kernel_base = 0, initrd_base = 0, cmdline_base = 0;
+    long kernel_size = 0, initrd_size = 0;
      UNINHostState *uninorth_pci;
      PCIBus *pci_bus;
      PCIDevice *macio;
@@ -130,7 +130,7 @@ static void ppc_core99_init(MachineState *machine)
      DeviceState *dev, *pic_dev;
      DeviceState *uninorth_internal_dev = NULL, *uninorth_agp_dev = NULL;
      hwaddr nvram_addr = 0xFFF04000;
-    uint64_t tbfreq;
+    uint64_t tbfreq = kvm_enabled() ? kvmppc_get_tbfreq() : TBFREQ;
        /* init CPUs */
      for (i = 0; i < machine->smp.cpus; i++) {
@@ -165,8 +165,6 @@ static void ppc_core99_init(MachineState *machine)
bios_size = load_image_targphys(filename, PROM_BASE, PROM_SIZE); 
          }
          g_free(filename);
-    } else {
-        bios_size = -1;
      }
      if (bios_size < 0 || bios_size > PROM_SIZE) {
          error_report("could not load PowerPC bios '%s'", bios_name);
@@ -174,15 +172,12 @@ static void ppc_core99_init(MachineState *machine)
      }
        if (machine->kernel_filename) {
-        int bswap_needed;
+        int bswap_needed = 0;
    #ifdef BSWAP_NEEDED
          bswap_needed = 1;
-#else
-        bswap_needed = 0;
  #endif
          kernel_base = KERNEL_LOAD_ADDR;
-
          kernel_size = load_elf(machine->kernel_filename, NULL,
translate_kernel_address, NULL, NULL, NULL, 
                                 NULL, NULL, 1, PPC_ELF_MACHINE, 0, 0);
@@ -212,16 +207,10 @@ static void ppc_core99_init(MachineState *machine)
              }
              cmdline_base = TARGET_PAGE_ALIGN(initrd_base + initrd_size);
          } else {
-            initrd_base = 0;
-            initrd_size = 0;


This bit seems a bit odd...
cmdline_base = TARGET_PAGE_ALIGN(kernel_base + kernel_size + KERNEL_GAP); 
          }
          ppc_boot_device = 'm';
      } else {
-        kernel_base = 0;
-        kernel_size = 0;
-        initrd_base = 0;
-        initrd_size = 0;
and also here. The only reason I can think that someone would explicitly set these variables back to 0 would be if there are cases in the load_*() functions where non-zero values could be returned for failure. It's worth having a look to confirm this and see if this also needs some additional tweaks to the logic flow here.
They aren't set back to 0 but set here the first time. Nothing touches these variables before this if-else do this patch just moves the zero init to the variable declaration and only leaves the cases which set a value different than zero here which I think is easier to follow. 

Regards,
BALATON Zoltan


          ppc_boot_device = '\0';
          /* We consider that NewWorld PowerMac never have any floppy drive
           * For now, OHW cannot boot from the network.
@@ -343,13 +332,6 @@ static void ppc_core99_init(MachineState *machine)
      has_adb = (core99_machine->via_config == CORE99_VIA_CONFIG_CUDA ||
                 core99_machine->via_config == CORE99_VIA_CONFIG_PMU_ADB);
  -    /* Timebase Frequency */
-    if (kvm_enabled()) {
-        tbfreq = kvmppc_get_tbfreq();
-    } else {
-        tbfreq = TBFREQ;
-    }
-
      /* init basic PC hardware */
      pci_bus = PCI_HOST_BRIDGE(uninorth_pci)->bus;
  diff --git a/hw/ppc/mac_oldworld.c b/hw/ppc/mac_oldworld.c
index 86512d31ad..cb67e44081 100644
--- a/hw/ppc/mac_oldworld.c
+++ b/hw/ppc/mac_oldworld.c
@@ -84,11 +84,11 @@ static void ppc_heathrow_init(MachineState *machine)
      PowerPCCPU *cpu = NULL;
      CPUPPCState *env = NULL;
      char *filename;
-    int i, bios_size;
+    int i, bios_size = -1;
      MemoryRegion *bios = g_new(MemoryRegion, 1);
      uint64_t bios_addr;
-    uint32_t kernel_base, initrd_base, cmdline_base = 0;
-    int32_t kernel_size, initrd_size;
+    uint32_t kernel_base = 0, initrd_base = 0, cmdline_base = 0;
+    int32_t kernel_size = 0, initrd_size = 0;
      PCIBus *pci_bus;
      PCIDevice *macio;
      MACIOIDEState *macio_ide;
@@ -99,7 +99,7 @@ static void ppc_heathrow_init(MachineState *machine)
      uint16_t ppc_boot_device;
      DriveInfo *hd[MAX_IDE_BUS * MAX_IDE_DEVS];
      void *fw_cfg;
-    uint64_t tbfreq;
+    uint64_t tbfreq = kvm_enabled() ? kvmppc_get_tbfreq() : TBFREQ;
        /* init CPUs */
      for (i = 0; i < machine->smp.cpus; i++) {
@@ -139,8 +139,6 @@ static void ppc_heathrow_init(MachineState *machine)
              bios_addr = PROM_BASE;
          }
          g_free(filename);
-    } else {
-        bios_size = -1;
      }
      if (bios_size < 0 || bios_addr - PROM_BASE + bios_size > PROM_SIZE) {
          error_report("could not load PowerPC bios '%s'", bios_name);
@@ -148,12 +146,10 @@ static void ppc_heathrow_init(MachineState *machine)
      }
        if (machine->kernel_filename) {
-        int bswap_needed;
+        int bswap_needed = 0;
    #ifdef BSWAP_NEEDED
          bswap_needed = 1;
-#else
-        bswap_needed = 0;
  #endif
          kernel_base = KERNEL_LOAD_ADDR;
          kernel_size = load_elf(machine->kernel_filename, NULL,
@@ -186,16 +182,10 @@ static void ppc_heathrow_init(MachineState *machine)
              }
              cmdline_base = TARGET_PAGE_ALIGN(initrd_base + initrd_size);
          } else {
-            initrd_base = 0;
-            initrd_size = 0;
cmdline_base = TARGET_PAGE_ALIGN(kernel_base + kernel_size + KERNEL_GAP); 
          }
          ppc_boot_device = 'm';
      } else {
-        kernel_base = 0;
-        kernel_size = 0;
-        initrd_base = 0;
-        initrd_size = 0;
          ppc_boot_device = '\0';
          for (i = 0; machine->boot_config.order[i] != '\0'; i++) {
              /*
@@ -223,13 +213,6 @@ static void ppc_heathrow_init(MachineState *machine)
          }
      }
  -    /* Timebase Frequency */
-    if (kvm_enabled()) {
-        tbfreq = kvmppc_get_tbfreq();
-    } else {
-        tbfreq = TBFREQ;
-    }
-
      /* Grackle PCI host bridge */
      grackle_dev = qdev_new(TYPE_GRACKLE_PCI_HOST_BRIDGE);
      qdev_prop_set_uint32(grackle_dev, "ofw-addr", 0x80000000);


... and obviously the same comments for mac_oldworld.c too.


ATB,

Mark.
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