gcc - Documentation about inline gas -

While reading the Linux 0.01 kernel, I remove some inline gas which is difficult for me to understand:

  __ asm __ ("movl $ 0x3ff000, %% eax \ n \ t" "movl %% eax, %% db0 \ n \ t" "movl $ 0x000d0303, %% ex \ n \ t" movl %% Eax, %% db7 ":::" ax ")  

or

  __ asm __ (" push %% fs; mov% ax axis, %% Fs; movl %% fs:% 2, %% eax; pop %% fs "\:" = a "(__race):" 0 "(seg)," m "(* (end)); \ __res;})  

I do not understand how the contents are interpreted in the middle of the ':'.

Have some documents about?

Thanks

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