Created attachment 106468 [details]
c++ host

Today I tested how two uniform buffers work in mesa and find a bug, when unable to edit second buffer. It's happen when you uses values from uniform buffers to create vec4.

Vertex shader:
#version 330 core

uniform test_unif1
{
    float test1;
    float test2;
};

uniform test_unif2
{
    float test3;
    float test4;
};

in vec4 pos;
out vec4 fcolor;

void main(void)
{
    gl_Position = pos;
    fcolor = vec4(test1,test2,test3,test4);
}

test3 and test4 is unchangeable from c++ host. If I do this:

gl_Position = test4 * pos;
fcolor = vec4(test1,test2,test3,1.0f);

test3 and test4 will work ok. So I think it's a bug of driver.
Radeon 6480g + radeon 7470m. Ubuntu 14.10. Drivers from oibaf ppa.