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Re: [Qemu-devel] [RFC PATCH 05/11] target/arm: fixup some of the comment
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [Qemu-devel] [RFC PATCH 05/11] target/arm: fixup some of the commentary for arm-semi |
Date: |
Tue, 14 May 2019 18:56:07 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 |
On 5/14/19 5:52 PM, Alex Bennée wrote:
> This cleans up a number of the block comments to fit the proper style.
> While we are at it we also reference the official specification and
> document what the return register value can be.
>
> Signed-off-by: Alex Bennée <address@hidden>
Reviewed-by: Philippe Mathieu-Daudé <address@hidden>
> ---
> target/arm/arm-semi.c | 40 +++++++++++++++++++++++++++++++---------
> 1 file changed, 31 insertions(+), 9 deletions(-)
>
> diff --git a/target/arm/arm-semi.c b/target/arm/arm-semi.c
> index 3273306c8ea..9e5a414dd89 100644
> --- a/target/arm/arm-semi.c
> +++ b/target/arm/arm-semi.c
> @@ -2,6 +2,7 @@
> * Arm "Angel" semihosting syscalls
> *
> * Copyright (c) 2005, 2007 CodeSourcery.
> + * Copyright (c) 2019 Linaro
> * Written by Paul Brook.
> *
> * This program is free software; you can redistribute it and/or modify
> @@ -16,6 +17,10 @@
> *
> * You should have received a copy of the GNU General Public License
> * along with this program; if not, see <http://www.gnu.org/licenses/>.
> + *
> + * ARM Semihosting is documented in:
> + * Semihosting for AArch32 and AArch64 Release 2.0
> + * https://static.docs.arm.com/100863/0200/semihosting.pdf
> */
>
> #include "qemu/osdep.h"
> @@ -240,6 +245,15 @@ static target_ulong arm_gdb_syscall(ARMCPU *cpu,
> gdb_syscall_complete_cb cb,
> put_user_u64(val, args + (n) * 8) : \
> put_user_u32(val, args + (n) * 4))
>
> +/*
> + * Do a semihosting call.
> + *
> + * The specification always says that the "return register" either
> + * returns a specific value or is corrupted, so we don't need to
> + * report to our caller whether we are returning a value or trying to
> + * leave the register unchanged. We use 0xdeadbeef as the return value
> + * when there isn't a defined return value for the call.
> + */
> target_ulong do_arm_semihosting(CPUARMState *env)
> {
> ARMCPU *cpu = arm_env_get_cpu(env);
> @@ -510,14 +524,16 @@ target_ulong do_arm_semihosting(CPUARMState *env)
>
> output_size = ts->info->arg_end - ts->info->arg_start;
> if (!output_size) {
> - /* We special-case the "empty command line" case (argc==0).
> - Just provide the terminating 0. */
> + /*
> + * We special-case the "empty command line" case (argc==0).
> + * Just provide the terminating 0.
> + */
> output_size = 1;
> }
> #endif
>
> if (output_size > input_size) {
> - /* Not enough space to store command-line arguments. */
> + /* Not enough space to store command-line arguments. */
> return -1;
> }
>
> @@ -571,8 +587,10 @@ target_ulong do_arm_semihosting(CPUARMState *env)
> GET_ARG(0);
>
> #ifdef CONFIG_USER_ONLY
> - /* Some C libraries assume the heap immediately follows .bss, so
> - allocate it using sbrk. */
> + /*
> + * Some C libraries assume the heap immediately follows .bss, so
> + * allocate it using sbrk.
> + */
> if (!ts->heap_limit) {
> abi_ulong ret;
>
> @@ -620,7 +638,8 @@ target_ulong do_arm_semihosting(CPUARMState *env)
> }
> case TARGET_SYS_EXIT:
> if (is_a64(env)) {
> - /* The A64 version of this call takes a parameter block,
> + /*
> + * The A64 version of this call takes a parameter block,
> * so the application-exit type can return a subcode which
> * is the exit status code from the application.
> */
> @@ -633,14 +652,17 @@ target_ulong do_arm_semihosting(CPUARMState *env)
> ret = 1;
> }
> } else {
> - /* ARM specifies only Stopped_ApplicationExit as normal
> - * exit, everything else is considered an error */
> + /*
> + * ARM specifies only Stopped_ApplicationExit as normal
> + * exit, everything else is considered an error
> + */
> ret = (args == ADP_Stopped_ApplicationExit) ? 0 : 1;
> }
> gdb_exit(env, ret);
> exit(ret);
> case TARGET_SYS_SYNCCACHE:
> - /* Clean the D-cache and invalidate the I-cache for the specified
> + /*
> + * Clean the D-cache and invalidate the I-cache for the specified
> * virtual address range. This is a nop for us since we don't
> * implement caches. This is only present on A64.
> */
>
- [Qemu-devel] [RFC PATCH 00/11] semihosting cleanup and re-factor, Alex Bennée, 2019/05/14
- [Qemu-devel] [RFC PATCH 02/11] semihosting: introduce CONFIG_SEMIHOSTING, Alex Bennée, 2019/05/14
- [Qemu-devel] [RFC PATCH 03/11] semihosting: implement a semihosting console, Alex Bennée, 2019/05/14
- [Qemu-devel] [RFC PATCH 05/11] target/arm: fixup some of the commentary for arm-semi, Alex Bennée, 2019/05/14
- Re: [Qemu-devel] [RFC PATCH 05/11] target/arm: fixup some of the commentary for arm-semi,
Philippe Mathieu-Daudé <=
- [Qemu-devel] [RFC PATCH 10/11] target/mips: convert UHI_plog to use common semihosting code, Alex Bennée, 2019/05/14
- [Qemu-devel] [RFC PATCH 04/11] semihosting: enable chardev backed output for console, Alex Bennée, 2019/05/14
- [Qemu-devel] [RFC PATCH 06/11] target/arm: use the common interface for WRITE0/WRITEC in arm-semi, Alex Bennée, 2019/05/14