Summary:
Some old linux versions do not have process_vm_readv function defined. Even older versions do not
have even the __NR_process_vm_readv syscall number. We use cmake to detect these situations and
fallback appropriately: in the first case, we can issue the syscall manually, while it the latter
case, we need to drop fast memory read support completely.
Test Plan: linux test suite passes
Reviewers: ovyalov, Eugene.Zelenko
Subscribers: tberghammer, lldb-commits
Differential Revision: http://reviews.llvm.org/D10727
llvm-svn: 240927
Summary:
Memory reads using the ptrace API need to be executed on a designated thread
and in 4-byte increments. The process_vm_read syscall has no such requirements
and it is about 50 times faster. This patch makes lldb-server use the faster
API if the target kernel supports it. Kernel support for this feature is
determined at runtime. Using process_vm_writev in the same manner is more
complicated since this syscall (unlike ptrace) respects page protection settings
and so it cannot be used to set a breakpoint, since code pages are typically
read-only. However, memory writes are not currently a performance bottleneck as
they happen much more rarely.
Test Plan: all tests continue to pass
Reviewers: ovyalov, vharron
Subscribers: tberghammer, lldb-commits
Differential Revision: http://reviews.llvm.org/D10488
llvm-svn: 239924
Pavel Labath