Messages in this thread | | | Date | Tue, 09 Mar 1999 18:58:43 -0800 (PST) | From | Jeremy Fitzhardinge <> | Subject | Re: Linux/IA-64 byte order |
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On 10-Mar-99 Richard Gooch wrote: > Jeremy Fitzhardinge writes: >> On 09-Mar-99 Vladimir Dergachev wrote: >> > >> > Is it too stupid to suggest an "ENDIANNESS" flag for mmap ? The overhead >> > for loading a page from disk is much bigger than the overhead for >> > rearranging the bytes. (Perhaps it should be not a flag but an ioctl..) >> >> That would inhibit sharing between processes unless all mappings are >> for the same endianness. > > No, it wouldn't. Each process can map it as it pleases.
Vladmir is proposing having the kernel rearrange the bytes manually, rather than relying on hardware support. This wouldn't work for two reasons: - sharing wouldn't work with mappings of different endianness - the kernel can't do the required reversal, since it depends on the type of the data, but the kernel only sees raw bytes.
If the hardware has per-page endianness settings then neither of these apply.
J
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