Chris Wedgwood wrote:
On Thu, Sep 14, 2006 at 06:39:47PM -0700, [EMAIL PROTECTED] wrote:
Make PROT_WRITE imply PROT_READ for a number of architectures which
don't support write only in hardware.
Why don't we WARN where PROT_WRITE is used w/o PROT_READ? Do
non-trivial or non-contrived applications really use PROT_WRITE and
assume reads are OK?
It seems once we do this there will be little or no chance of ever
doing write-only mappings should we want to in the future using this
mechanism.
We could just update the definition of PROT_WRITE in the userspace
headers...
btw PROT_WRITE does make sense in principle for MMIO mappings, especially
uncachable ones. Not per se on native hardware, but in the hardware enabled
virtualization (Intel VT or AMD-V) case this suddenly becomes very easily
enforcable and probably even worth enforcing (since in that case the hypervisor
traps on each access to the memory and simulates the instruction anyway;
only writes means it's a lot simpler in terms of IOMMU and cache coherency etc
etc)
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