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Re: [Qemu-devel] [RFC][PATCH 11/15] memory: Allow unaligned address_spac
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [RFC][PATCH 11/15] memory: Allow unaligned address_space_rw |
Date: |
Mon, 06 May 2013 17:01:29 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4 |
Il 06/05/2013 16:58, Jan Kiszka ha scritto:
> On 2013-05-06 16:55, Paolo Bonzini wrote:
>> Il 06/05/2013 16:26, Jan Kiszka ha scritto:
>>> This will be needed for some corner cases with para-virtual the I/O
>>> ports.
>>>
>>> Signed-off-by: Jan Kiszka <address@hidden>
>>> ---
>>> exec.c | 33 ++++++++++++++++++---------------
>>> 1 files changed, 18 insertions(+), 15 deletions(-)
>>>
>>> diff --git a/exec.c b/exec.c
>>> index 3ee1f3f..9c582b1 100644
>>> --- a/exec.c
>>> +++ b/exec.c
>>> @@ -1833,38 +1833,41 @@ void address_space_rw(AddressSpace *as, hwaddr
>>> addr, uint8_t *buf,
>>> uint8_t *ptr;
>>> uint32_t val;
>>> MemoryRegionSection *section;
>>> + MemoryRegion *mr;
>>>
>>> while (len > 0) {
>>> l = ((addr & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE) - addr;
>>> if (l > len)
>>> l = len;
>>> section = address_space_lookup_region(as, addr);
>>> + mr = section->mr;
>>>
>>> if (is_write) {
>>> - if (!memory_region_is_ram(section->mr)) {
>>> + if (!memory_region_is_ram(mr)) {
>>> hwaddr addr1;
>>> addr1 = memory_region_section_addr(section, addr);
>>> /* XXX: could force cpu_single_env to NULL to avoid
>>> potential bugs */
>>> - if (l >= 4 && ((addr1 & 3) == 0)) {
>>> + if (l >= 4 && ((addr1 & 3) == 0 ||
>>> mr->ops->impl.unaligned)) {
>>
>> Does the length matter at all if unaligned accesses are allowed? I
>> think it shouldn't...
>
> What do you mean? The length test here is not about alignment, it's
> about proper split-up depending on the input size (we cannot use 32 bit
> for all accesses and do not want to make them all byte accesses, do we?).
Oh right, I was thinking of my IOMMU tree where I have:
l = len;
section = address_space_translate(as, addr, &addr1, &l, is_write);
if (is_write) {
if (!memory_region_is_ram(section->mr)) {
/* XXX: could force cpu_single_env to NULL to avoid
potential bugs */
if (l >= 4 && ((addr1 & 3) == 0)) {
and address_space_translate does:
*plen = MIN(section->size - addr, *plen);
It should not do this if section->mr->ops.unaligned. Whoever rebases on top
of the other should keep this in mind.
Paolo
- Re: [Qemu-devel] [RFC][PATCH 10/15] memory: Rework sub-page handling, (continued)
[Qemu-devel] [RFC][PATCH 11/15] memory: Allow unaligned address_space_rw, Jan Kiszka, 2013/05/06
[Qemu-devel] [RFC][PATCH 09/15] memory: Introduce address_space_lookup_region, Jan Kiszka, 2013/05/06
[Qemu-devel] [RFC][PATCH 07/15] Privatize register_ioport_read/write, Jan Kiszka, 2013/05/06
[Qemu-devel] [RFC][PATCH 01/15] adlib: replace register_ioport*, Jan Kiszka, 2013/05/06
[Qemu-devel] [RFC][PATCH 04/15] i82374: replace register_ioport*, Jan Kiszka, 2013/05/06
[Qemu-devel] [RFC][PATCH 15/15] ioport: Move IOPortRead/WriteFunc typedefs to memory.h, Jan Kiszka, 2013/05/06
[Qemu-devel] [RFC][PATCH 13/15] ioport: Switch dispatching to memory core layer, Jan Kiszka, 2013/05/06
[Qemu-devel] [RFC][PATCH 05/15] prep: replace register_ioport*, Jan Kiszka, 2013/05/06