Re: [PATCH v4 2/4] xen: Add files needed for minimal ppc64le build

[Julien Grall <julien@xxxxxxx>]

Hi,

On 16/06/2023 21:24, Andrew Cooper wrote:
> > --- /dev/null
> > +++ b/xen/arch/ppc/ppc64/head.S
> > @@ -0,0 +1,27 @@
> > +/* SPDX-License-Identifier: GPL-2.0-or-later */
> > +
> > +.section .text.header, "ax", %progbits
> > +
> > +ENTRY(start)
> > +    /*
> > +     * Depending on how we were booted, the CPU could be running in either
> > +     * Little Endian or Big Endian mode. The following trampoline from Linux
> > +     * cleverly uses an instruction that encodes to a NOP if the CPU's
> > +     * endianness matches the assumption of the assembler (LE, in our case)
> > +     * or a branch to code that performs the endian switch in the other case.
> > +     */
> > +    tdi 0, 0, 0x48    /* Reverse endian of b . + 8          */
> > +    b . + 44          /* Skip trampoline if endian is good  */
> > +    .long 0xa600607d  /* mfmsr r11                          */
> > +    .long 0x01006b69  /* xori r11,r11,1                     */
> > +    .long 0x00004039  /* li r10,0                           */
> > +    .long 0x6401417d  /* mtmsrd r10,1                       */
> > +    .long 0x05009f42  /* bcl 20,31,$+4                      */
> > +    .long 0xa602487d  /* mflr r10                           */
> > +    .long 0x14004a39  /* addi r10,r10,20                    */
> > +    .long 0xa6035a7d  /* mtsrr0 r10                         */
> > +    .long 0xa6037b7d  /* mtsrr1 r11                         */
> > +    .long 0x2400004c  /* rfid                               */
> > +
> > +    /* Now that the endianness is confirmed, continue */
> > +1:  b 1b
> .size start, . - start
> .type start, %function
Shouldn't we introduce ENDPROC()/END() to avoid open-coding these two 
lines everywhere?
Cheers,

--
Julien Grall