X86 architecture DMA channel is not fixed right, on a certain motherboards ?

Such as the title , DMA , there are three , X86 is used which , it seems there is always 8 channels with 8 0,1,2,3 , 4,5,6,7 with 16 , but these are not all fixed through dead, than something with 4-channel card, 5-channel with the sound , there is why there are 32 , 64 dma channel
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general channels are fixed Ha Oh , this is hardware-related , as you know behind said 3264 is dma channel support transport address
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Yes, thank you on the second floor , I have to figure out , and your answer same.