arm/system/boot.S

9  * R0 - semihosting call number
10  * R1 - semihosting parameter
26 	.size		\name, . - \name
57 	ite EQ  // if-then-else. "EQ" is for if equal, else otherwise
79 	 *  PA[31:20] - Section Base Address
80 	 *  NS[19] - Non-secure bit
81 	 *  0[18] - Section (1 for Super Section)
82 	 *  nG[17] - Not global bit
83 	 *  S[16] - Shareable
84 	 *  TEX[14:12] - Memory Region Attributes
85 	 *  AP[15, 11:10] - Access Permission Bits
88 	 *  XN[4] - Execute never bit
89 	 *  C[3] - Memory Region Attributes
90 	 *  B[2] - Memory Region Attributes
92 	 *  PXN[0] - Privileged Execute Never
94 	 * r0 - point at the table
95 	 * r1 - address
96 	 * r2 - entry
97 	 * r3 - common section bits
98 	 * r4 - scratch
126 	orr r2, r2, #(1 << 10)			/* AP[0] = 1 => RO @ PL1 */
128 	lsr r4, r2, #(20 - 2)
136 	orr r2, r2, #(1 << 10)			/* AP[0] = 1 => RW @ PL1 */
139 	lsr r4, r2, #(20 - 2)
143 	 * DACR - Domain Control
151 	 * TTCBR - Translation Table Base Control Register
153 	 * EAE[31] = 0, 32-bit translation, short descriptor format
154 	 * N[2:0] = 5 ( TTBRO uses 31:14-5 => 9 bit lookup stage )
160 	 * TTBR0 -Translation Table Base Register 0
162 	 * [31:9] = Base address of table
171 	 * SCTLR- System Control Register
173    	 * TE[30] = 0, exceptions to A32 state
175 	 * EE[25] = 0, Little-endian
194 	STMFD sp!, {r0-r1}  // push r0, r1 onto stack
198 	LDMFD sp!, {r0-r1}  // pop r0, r1 from stack