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Re: [PATCH] Add Prefer_MAP_32BIT_EXEC for Silvermont
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Andi Kleen <andi at firstfloor dot org>
- Cc: Zack Weinberg <zackw at panix dot com>, Adhemerval Zanella <adhemerval dot zanella at linaro dot org>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Fri, 11 Dec 2015 13:14:25 -0800
- Subject: Re: [PATCH] Add Prefer_MAP_32BIT_EXEC for Silvermont
- Authentication-results: sourceware.org; auth=none
- References: <20151211143706 dot GA7868 at intel dot com> <alpine dot DEB dot 2 dot 10 dot 1512111539300 dot 17023 at digraph dot polyomino dot org dot uk> <CAMe9rOqbqyFw3CMa35vwOEefdFq1xK2Q9hX8GXoGMKVZ-A2y0g at mail dot gmail dot com> <566AF894 dot 4060300 at linaro dot org> <CAMe9rOr-LypZXvq4Y4uwE_JybYoTXctZXMLjo4TH517NnC6omg at mail dot gmail dot com> <566B01BE dot 1070703 at linaro dot org> <CAKCAbMhMArQ9wsXhw2y+Fvv+_3O5i4g8pdDQdWo6_1YxqfVxkQ at mail dot gmail dot com> <CAMe9rOrVjSnhp-EzmAnVBg10wbqk9U4n+hL-3xF5=DPZP5co1A at mail dot gmail dot com> <CAKCAbMhk69hUBbrQ=0j0NDYjRT6R-EK1+F43+Mmi9FwS7epexQ at mail dot gmail dot com> <CAKCAbMhA6x4r6Bhw8cnAavoWzjWsm6WM8JPzrnCsrqxbEswS_g at mail dot gmail dot com> <87egeszoq3 dot fsf at tassilo dot jf dot intel dot com>
On Fri, Dec 11, 2015 at 12:59 PM, Andi Kleen <andi@firstfloor.org> wrote:
>
>
> BTW the patch could be fixed to support all 4GB by guessing a hole
> and using the mmap hint. But it would complicate it somewhat.
>
That means user space has to keep track mmap/mremap/munmap.
It isn't going to work.
We need a new MAP_4GB bit to get 4GB address and we can make it
backward compatible with old kernels. Can we extend the 64-bit
mmap interface to pass the extra bit in upper 32bits of the 5th argument
if we have run out bits in the 5th argument.
--
H.J.