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Re: [PATCH v6 1/3] memory: drop guest writes to read-only ram device reg
From: |
Yan Zhao |
Subject: |
Re: [PATCH v6 1/3] memory: drop guest writes to read-only ram device regions |
Date: |
Mon, 25 May 2020 22:11:46 -0400 |
User-agent: |
Mutt/1.9.4 (2018-02-28) |
On Mon, May 25, 2020 at 01:04:56PM +0200, Paolo Bonzini wrote:
> On 25/05/20 12:54, Philippe Mathieu-Daudé wrote:
> >> Not all of them, only those that need to return MEMTX_ERROR. I would
> >> like some guidance from Peter as to whether (or when) reads from ROMs
> >> should return MEMTX_ERROR. This way, we can use that information to
> >> device what the read-only ram-device regions should do.
> > Is it only device-specific or might it be partly arch/machine-specific
> > (depending on the bus it is mapped)?
>
> Good point, I think that could be handled by propagating the error up in
> the memory region hierarchy (i.e. the cached AddressSpaceDispatch radix
> tree is used in the common case, but when you have a failure you
> percolate it up through the whole hierarchy since that's not a fast path).
>
>
but if we decide to propagate the error up by providing with
ops->write_with_attrs, then we have to remove ops->write correspondingly.
as in
memory_region_dispatch_write()
{
...
if (mr->ops->write) {
return access_with_adjusted_size(addr, &data, size,
mr->ops->impl.min_access_size,
mr->ops->impl.max_access_size,
memory_region_write_accessor, mr,
attrs);
} else {
return
access_with_adjusted_size(addr, &data, size,
mr->ops->impl.min_access_size,
mr->ops->impl.max_access_size,
memory_region_write_with_attrs_accessor,
mr, attrs);
}
...
}
so which regions should keep ops->write and which regions should not?
Thanks
Yan
- Re: [PATCH v6 1/3] memory: drop guest writes to read-only ram device regions, Paolo Bonzini, 2020/05/21
- Re: [PATCH v6 1/3] memory: drop guest writes to read-only ram device regions, Peter Maydell, 2020/05/26
- Re: [PATCH v6 1/3] memory: drop guest writes to read-only ram device regions, Yan Zhao, 2020/05/28
- Re: [PATCH v6 1/3] memory: drop guest writes to read-only ram device regions, Paolo Bonzini, 2020/05/28
- Re: [PATCH v6 1/3] memory: drop guest writes to read-only ram device regions, Yan Zhao, 2020/05/28