The bug here is that the DRI context "flags" are intended to alias the
GLX context flag values, and they don't, DRI's no-error flag is GLX's
reset-isolation flag. GLX (and EGL!) treat no-error as a context
attribute, and reset isolation predates Mesa's no-error implementation
by several years. The GL_KHR_no_error spec does describe it as a
"context flag", though, so maybe that's why we do it as a (DRI) context
flag.
In order to unalias these we need a new contract with the loader. We
remove the old __DRI_NO_ERROR extension, and add a new
__DRI_RENDERER_HAS_CONTEXT_NO_ERROR value to query. Loaders can key on
that to know to pass no-error-ness through as a context attribute,
matching the GLX/EGL calling convention. We go ahead and define
__DRI_CTX_FLAG_RESET_ISOLATION as well, and update the drivers to refuse
it since we don't support it yet.
This means mismatched drivers/loaders will not be able to create
no-error contexts. Too bad. If you want performance that badly you can
build both things at once.
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12474>
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