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author | Florian Weimer <fweimer@redhat.com> | 2019-10-07 19:03:50 +0200 |
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committer | Florian Weimer <fweimer@redhat.com> | 2019-10-07 19:03:51 +0200 |
commit | 921abe47299255a6480456c98fbb53bdc5db92a2 (patch) | |
tree | e8201c2596a51eacfadcad4f030373fba6df2fad /hesiod | |
parent | 0caab6638e22a301e8aa0b35f790b15aaf0791d9 (diff) | |
download | glibc-921abe47299255a6480456c98fbb53bdc5db92a2.zip glibc-921abe47299255a6480456c98fbb53bdc5db92a2.tar.gz glibc-921abe47299255a6480456c98fbb53bdc5db92a2.tar.bz2 |
riscv: Remove support for variable page sizes
_dl_var_init is used to patch the read-only data section after
relocation. Several architectures use this to update
GLRO(page_size) with the correct value for the static dlopen case,
where _rtld_global_ro has not been initialized by the dynamic
loader.
RISC-V does not need this. The RISC-V Instruction Set Manual,
Volume II: Privileged Architecture, Document Version
20190608-Priv-MSU-Ratified says this:
After much deliberation, we have settled on a conventional
page size of 4 KiB for both RV32 and RV64. We expect this
decision to ease the porting of low-level runtime software
and device drivers. The TLB reach problem is ameliorated by
transparent superpage support in modern operating systems
[2]. Additionally, multi-level TLB hierarchies are quite
inexpensive relative to the multi-level cache hierarchies
whose address space they map.
[2] Juan Navarro, Sitaram Iyer, Peter Druschel, and
Alan Cox. Practical, transparent operating system support
for superpages. SIGOPS Oper. Syst. Rev., 36(SI):89–104,
December 2002.
This means that the initialization of
_rtld_global_ro._dl_page_size in elf/rtld.c with EXEC_PAGESIZE
is sufficient for RISC-V.
Diffstat (limited to 'hesiod')
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