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The QEMU_UNINITIALIZED macro is to be used to skip the default compiler variable initialization done by -ftrivial-auto-var-init=zero. Use this in cases where there a method in the device I/O path (or other important hot paths), that has large variables on the stack. A rule of thumb is that "large" means a method with 4kb data in the local stack frame. Any variables which are KB in size, should be annotated with this attribute, to pre-emptively eliminate any potential overhead from the compiler zero'ing memory. Given that this turns off a security hardening feature, when using this to flag variables, it is important that the code is double-checked to ensure there is no possible use of uninitialized data in the method. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Message-id: 20250610123709.835102-2-berrange@redhat.com [DB: split off patch & rewrite guidance on when to use the annotation] Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> |
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| accel | ||
| authz | ||
| block | ||
| chardev | ||
| crypto | ||
| disas | ||
| exec | ||
| fpu | ||
| gdbstub | ||
| hw | ||
| io | ||
| libdecnumber | ||
| migration | ||
| monitor | ||
| net | ||
| qapi | ||
| qemu | ||
| qobject | ||
| qom | ||
| scsi | ||
| semihosting | ||
| standard-headers | ||
| system | ||
| tcg | ||
| ui | ||
| user | ||
| elf.h | ||
| glib-compat.h | ||
| qemu-io.h | ||
| qemu-main.h | ||