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Re: [Qemu-devel] [PATCH v3 16/16] [RFC] dma/rc4030: do multiple calls to
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH v3 16/16] [RFC] dma/rc4030: do multiple calls to address_space_rw when doing DMA transfers |
Date: |
Wed, 10 Jun 2015 21:20:45 +0100 |
On 10 June 2015 at 20:37, Hervé Poussineau <address@hidden> wrote:
> Hi Leon,
>
>
> Le 10/06/2015 14:00, Leon Alrae a écrit :
>>
>> Hi Hervé,
>>
>> On 03/06/2015 21:45, Hervé Poussineau wrote:
>>>
>>> This fixes Windows NT 4.0/MIPS, which was always bugchecking with
>>> IRQL_NOT_LESS_OR_EQUAL.
>>>
>>> Signed-off-by: Hervé Poussineau <address@hidden>
>>> ---
>>> hw/dma/rc4030.c | 14 ++++++++++++--
>>> 1 file changed, 12 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/hw/dma/rc4030.c b/hw/dma/rc4030.c
>>> index 3efa6de..deac0a8 100644
>>> --- a/hw/dma/rc4030.c
>>> +++ b/hw/dma/rc4030.c
>>> @@ -681,6 +681,7 @@ static void rc4030_do_dma(void *opaque, int n,
>>> uint8_t *buf, int len, int is_wri
>>> rc4030State *s = opaque;
>>> hwaddr dma_addr;
>>> int dev_to_mem;
>>> + int i;
>>>
>>> s->dma_regs[n][DMA_REG_ENABLE] &= ~(DMA_FLAG_TC_INTR |
>>> DMA_FLAG_MEM_INTR | DMA_FLAG_ADDR_INTR);
>>>
>>> @@ -699,8 +700,17 @@ static void rc4030_do_dma(void *opaque, int n,
>>> uint8_t *buf, int len, int is_wri
>>> dma_addr = s->dma_regs[n][DMA_REG_ADDRESS];
>>>
>>> /* Read/write data at right place */
>>> - address_space_rw(&s->dma_as, dma_addr, MEMTXATTRS_UNSPECIFIED,
>>> - buf, len, is_write);
>>> + for (i = 0; i < len; ) {
>>> + int ncpy = DMA_PAGESIZE - (dma_addr & (DMA_PAGESIZE - 1));
>>> + if (ncpy > len - i) {
>>> + ncpy = len - i;
>>> + }
>>> + address_space_rw(&s->dma_as, dma_addr, MEMTXATTRS_UNSPECIFIED,
>>> + buf + i, ncpy, is_write);
>>> +
>>> + dma_addr += ncpy;
>>> + i += ncpy;
>>> + }
>>>
>>> s->dma_regs[n][DMA_REG_ENABLE] |= DMA_FLAG_TC_INTR;
>>> s->dma_regs[n][DMA_REG_COUNT] -= len;
>>>
>>
>> I'm sending out current target-mips queue soon and I can include this
>> series,
>> but I'm not quite sure what to do with this RFC patch. I presume you put
>> RFC
>> here because it's a workaround for a bug, but it's not clear where the
>> actual
>> bug is?
>
>
> Indeed, that's a workaround for a bug that I failed to identify. You can
> still take the RFC patch as a patch, as I didn't see any objection (yet).
> I think we can defer the bug correction for later.
...but address_space_rw() is supposed to be the same as if
you do a bunch of shorter writes, so if we have a problem
in the memory system core we should really track it down...
Paolo, does this look familiar at all?
-- PMM
- [Qemu-devel] [PATCH v3 09/16] net/dp8393x: do not use old_mmio accesses, (continued)
- [Qemu-devel] [PATCH v3 09/16] net/dp8393x: do not use old_mmio accesses, Hervé Poussineau, 2015/06/03
- [Qemu-devel] [PATCH v3 03/16] dma/rc4030: use AddressSpace and address_space_rw in users, Hervé Poussineau, 2015/06/03
- [Qemu-devel] [PATCH v3 13/16] net/dp8393x: add load/save support, Hervé Poussineau, 2015/06/03
- [Qemu-devel] [PATCH v3 15/16] net/dp8393x: fix hardware reset, Hervé Poussineau, 2015/06/03
- [Qemu-devel] [PATCH v3 14/16] net/dp8393x: correctly reset in_use field, Hervé Poussineau, 2015/06/03
- [Qemu-devel] [PATCH v3 10/16] net/dp8393x: use dp8393x_ prefix for all functions, Hervé Poussineau, 2015/06/03
- [Qemu-devel] [PATCH v3 11/16] net/dp8393x: QOM'ify, Hervé Poussineau, 2015/06/03
- [Qemu-devel] [PATCH v3 16/16] [RFC] dma/rc4030: do multiple calls to address_space_rw when doing DMA transfers, Hervé Poussineau, 2015/06/03
- [Qemu-devel] [PATCH v3 12/16] net/dp8393x: add PROM to store MAC address, Hervé Poussineau, 2015/06/03