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Re: [Qemu-block] [Qemu-devel] [PATCH] fdc: remove sparc sun4m mutations

From: Hervé Poussineau
Subject: Re: [Qemu-block] [Qemu-devel] [PATCH] fdc: remove sparc sun4m mutations
Date: Tue, 17 Mar 2015 07:43:55 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.4.0


Le 16/03/2015 22:48, John Snow a écrit :
On 03/14/2015 12:50 PM, Hervé Poussineau wrote:
They were introduced in 6f7e9aec5eb5bdfa57a9e458e391b785c283a007 and
82407d1a4035e5bfefb53ffdcb270872f813b34c and lots of bug fixes were done after 

This fixes (at least) the detection of the floppy controller on Debian 
and SS-5's OBP initialization routine still works.

Removing workaround code from six years ago in a device we hardly touch seems 
sane to me if it doesn't appear to break the machine it was originally 
architected for (SS-5, from 82407d1a's commit
message), but I am not well versed in SPARC configurations, unfortunately for 
us :)

It appears this quirk is active for a wide number of machine configurations 
(basically all that appear under sun4m_machine_init) -- What's the risk of us 
breaking one of those configurations?

How did you test SS-5? (Can we test the others similarly? Is there a 
justification for not doing so?)

According to 82407d1a4035e5bfefb53ffdcb270872f813b34c, there was probably a hang when SS-5 OBP firmware was initializing the floppy. I checked my change with the OBP SS-5 firmware 2.15, which doesn't hang and goes up to firmware prompt. I also tested SS-4, SS-10 (OBP v3.45) and SS-20 (OBP 2.25) which also go up to firmware prompt. I was unable to test the other platforms with OBP.
Then, I tested SS-5 with Debian 4.0r9, and boot messages now detect the floppy controller with 
"Floppy drive(s): fd0 is 1.44M" and "FDC 0 is a S82078B"

However, in 82407d1a4035e5bfefb53ffdcb270872f813b34c, floppy was probably not 
working, and is still broken after this commit. This may be due to a missing 
DMA controller on sparc platform.




Signed-off-by: Hervé Poussineau <address@hidden>
  hw/block/fdc.c |   17 -----------------
  1 file changed, 17 deletions(-)

diff --git a/hw/block/fdc.c b/hw/block/fdc.c
index 2bf87c9..f72a392 100644
--- a/hw/block/fdc.c
+++ b/hw/block/fdc.c
@@ -535,8 +535,6 @@ struct FDCtrl {
      uint8_t pwrd;
      /* Floppy drives */
      uint8_t num_floppies;
-    /* Sun4m quirks? */
-    int sun4m;
      FDrive drives[MAX_FD];
      int reset_sensei;
      uint32_t check_media_rate;
@@ -885,13 +883,6 @@ static void fdctrl_reset_irq(FDCtrl *fdctrl)

  static void fdctrl_raise_irq(FDCtrl *fdctrl)
-    /* Sparc mutation */
-    if (fdctrl->sun4m && (fdctrl->msr & FD_MSR_CMDBUSY)) {
-        /* XXX: not sure */
-        fdctrl->msr &= ~FD_MSR_CMDBUSY;
-        fdctrl->msr |= FD_MSR_RQM | FD_MSR_DIO;
-        return;
-    }
      if (!(fdctrl->sra & FD_SRA_INTPEND)) {
          qemu_set_irq(fdctrl->irq, 1);
          fdctrl->sra |= FD_SRA_INTPEND;
@@ -1080,12 +1071,6 @@ static uint32_t fdctrl_read_main_status(FDCtrl *fdctrl)
      fdctrl->dsr &= ~FD_DSR_PWRDOWN;
      fdctrl->dor |= FD_DOR_nRESET;

-    /* Sparc mutation */
-    if (fdctrl->sun4m) {
-        retval |= FD_MSR_DIO;
-        fdctrl_reset_irq(fdctrl);
-    };
      FLOPPY_DPRINTF("main status register: 0x%02x\n", retval);

      return retval;
@@ -2241,8 +2226,6 @@ static void sun4m_fdc_initfn(Object *obj)
      FDCtrlSysBus *sys = SYSBUS_FDC(obj);
      FDCtrl *fdctrl = &sys->state;

-    fdctrl->sun4m = 1;
      memory_region_init_io(&fdctrl->iomem, obj, &fdctrl_mem_strict_ops,
                            fdctrl, "fdctrl", 0x08);
      sysbus_init_mmio(sbd, &fdctrl->iomem);

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