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[Qemu-devel] Re: [PATCH v4 05/15] pci/bridge: fix pci_bridge_reset()
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] Re: [PATCH v4 05/15] pci/bridge: fix pci_bridge_reset() |
Date: |
Mon, 18 Oct 2010 09:08:09 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Mon, Oct 18, 2010 at 04:10:17PM +0900, Isaku Yamahata wrote:
> On Mon, Oct 18, 2010 at 08:22:24AM +0200, Michael S. Tsirkin wrote:
> > On Mon, Oct 18, 2010 at 12:17:46PM +0900, Isaku Yamahata wrote:
> > > lower 4bits of base/limit register is RO, and
> > > should not be modified on reset.
> > >
> > > Signed-off-by: Isaku Yamahata <address@hidden>
> > > ---
> > > hw/pci_bridge.c | 15 +++++++++------
> > > 1 files changed, 9 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/hw/pci_bridge.c b/hw/pci_bridge.c
> > > index 638e3b3..7229610 100644
> > > --- a/hw/pci_bridge.c
> > > +++ b/hw/pci_bridge.c
> > > @@ -161,12 +161,15 @@ void pci_bridge_reset_reg(PCIDevice *dev)
> > > conf[PCI_SUBORDINATE_BUS] = 0;
> > > conf[PCI_SEC_LATENCY_TIMER] = 0;
> > >
> > > - conf[PCI_IO_BASE] = 0;
> > > - conf[PCI_IO_LIMIT] = 0;
> > > - pci_set_word(conf + PCI_MEMORY_BASE, 0);
> > > - pci_set_word(conf + PCI_MEMORY_LIMIT, 0);
> > > - pci_set_word(conf + PCI_PREF_MEMORY_BASE, 0);
> > > - pci_set_word(conf + PCI_PREF_MEMORY_LIMIT, 0);
> > > + pci_clear_bit_byte(conf + PCI_IO_BASE, PCI_IO_RANGE_MASK & 0xff);
> > > + pci_clear_bit_byte(conf + PCI_IO_LIMIT, PCI_IO_RANGE_MASK & 0xff);
> >
> > No need for & 0xff and & 0xfffff here and below.
>
> gcc complains like this without them.
> hw/pci_bridge.c:165: error: large integer implicitly truncated to unsigned
> type
I see.
>
> > also, PCI spec also says that these registers' value
> > is undefined after reset, so no need to clear them?
> > If there's a reason, pls put it in comment.
>
> The spec says the lower bits are read-only and they have its meaning.
Yes. but my question is why even touch io base/io limit at all
in this function?
It looks like guest can not rely on these being 0 after reset.
> Anyway I'll add the reference as comment.
>
> For example.
>
> > 3.2.5.6 I/O Base Register and I/O Limit Register
> >
> > If the low four bits of the I/O Base and I/O Limit registers are 01h,
> > then the bridge supports 32-bit I/O address decoding, and the I/O Base
> > Upper 16 Bits and the I/O Limit Upper 16 Bits hold the upper 16 bits,
> > corresponding to AD[31::16], of the 32-bit I/O Base and I/O Limit
> > addresses respectively. In this case, system configuration software is
> > permitted to locate the I/O address range supported by the bridge
> > anywhere in the 4-GB I/O Space. Note that the 4-KB alignment and
> > granularity restrictions still apply when the bridge supports 32-bit
> > I/O addressing.
> > table 3-7
I don't think this is required but up to you.
> >
> >
> > > + pci_clear_bit_word(conf + PCI_MEMORY_BASE, PCI_MEMORY_RANGE_MASK &
> > > 0xffff);
> > > + pci_clear_bit_word(conf + PCI_MEMORY_LIMIT,
> > > + PCI_MEMORY_RANGE_MASK & 0xffff);
> > > + pci_clear_bit_word(conf + PCI_PREF_MEMORY_BASE,
> > > + PCI_PREF_RANGE_MASK & 0xffff);
> > > + pci_clear_bit_word(conf + PCI_PREF_MEMORY_LIMIT,
> > > + PCI_PREF_RANGE_MASK & 0xffff);
> > > pci_set_word(conf + PCI_PREF_BASE_UPPER32, 0);
> > > pci_set_word(conf + PCI_PREF_LIMIT_UPPER32, 0);
> > >
> > > --
> > > 1.7.1.1
> >
>
> --
> yamahata
- [Qemu-devel] Re: [PATCH v4 12/15] x3130: pcie upstream port, (continued)
- [Qemu-devel] [PATCH v4 01/15] pci: make pci_del_capability() update for w1cmask, Isaku Yamahata, 2010/10/17
- [Qemu-devel] [PATCH v4 08/15] pcie: helper functions for pcie capability and extended capability, Isaku Yamahata, 2010/10/17
- [Qemu-devel] [PATCH v4 15/15] pcie/aer: glue aer error injection into qemu monitor, Isaku Yamahata, 2010/10/17
- [Qemu-devel] [PATCH v4 14/15] pcie/hotplug: introduce pushing attention button command, Isaku Yamahata, 2010/10/17
- [Qemu-devel] [PATCH v4 05/15] pci/bridge: fix pci_bridge_reset(), Isaku Yamahata, 2010/10/17
[Qemu-devel] [PATCH v4 02/15] pci: introduce helper functions to clear/set bits in configuration space, Isaku Yamahata, 2010/10/17
[Qemu-devel] [PATCH v4 07/15] pcie: add pcie constants to pcie_regs.h, Isaku Yamahata, 2010/10/17
[Qemu-devel] [PATCH v4 11/15] ioh3420: pcie root port in X58 ioh, Isaku Yamahata, 2010/10/17
[Qemu-devel] [PATCH v4 04/15] pci: record which is written into pci configuration space, Isaku Yamahata, 2010/10/17