qemu: Add --allow-mmap to virtiofsd for mmap support#201
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The --cache=never flag (added in 50e7601 to avoid FD exhaustion) has a side effect: the guest kernel returns ENODEV for mmap() syscalls on virtiofs files. This breaks nontrivial use cases; while glibc has a fallback for failure to `mmap()` other tools don't. Assisted-by: OpenCode (claude-sonnet-4-20250514) Signed-off-by: Colin Walters <walters@verbum.org>
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This pull request adds the --allow-mmap flag to the virtiofsd command to re-enable mmap() support, which was broken by a previous change that introduced --cache=never. This is a necessary fix for supporting dynamically linked executables and other applications that rely on mmap. The change is accompanied by a new integration test that correctly verifies the fix. The implementation is sound. I have one suggestion to improve the Python script in the new test for better resource management.
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The --cache=never flag (added in 50e7601 to avoid FD exhaustion) has a side effect: the guest kernel returns ENODEV for mmap() syscalls on virtiofs files. This breaks nontrivial use cases; while glibc has a fallback for failure to
mmap()other tools don't.Assisted-by: OpenCode (claude-sonnet-4-20250514)