[U-Boot] [PATCH] config_distro_bootcmd.h: add note on error handling

[U-Boot] [PATCH] config_distro_bootcmd.h: add note on error handling

[Stephen Warren]

From: Stephen Warren <swarren@nvidia.com>

This should make it more clear why there appear to be C pre-processor
symbols in the file that contain mixed case. They're really error
messages.

Suggested-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
---
 include/config_distro_bootcmd.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/include/config_distro_bootcmd.h b/include/config_distro_bootcmd.h
index 07a0b3b23472..73f093f9eaf5 100644
--- a/include/config_distro_bootcmd.h
+++ b/include/config_distro_bootcmd.h
@@ -10,6 +10,22 @@
 #ifndef _CONFIG_CMD_DISTRO_BOOTCMD_H
 #define _CONFIG_CMD_DISTRO_BOOTCMD_H
 
+/*
+ * A note on error handling: It is possible for BOOT_TARGET_DEVICES to
+ * reference a device that is not enabled in the U-Boot configuration, e.g.
+ * it may include MMC in the list without CONFIG_CMD_MMC being enabled. Given
+ * that BOOT_TARGET_DEVICES is a macro that's expanded by the C pre-processor
+ * at compile time, it's not  possible to detect and report such problems via
+ * a simple #ifdef/#error combination. Still, the code needs to report errors.
+ * The best way I've found to do this is to make BOOT_TARGET_DEVICES expand to
+ * reference a non-existent symbol, and have the name of that symbol encode
+ * the error message. Consequently, this file contains references to e.g.
+ * BOOT_TARGET_DEVICES_references_MMC_without_CONFIG_CMD_MMC. Given the
+ * prevalence of capitals here, this looks like a pre-processor macro and
+ * hence seems like it should be all capitals, but it's really an error
+ * message that includes some other pre-processor symbols in the text.
+ */
+
 /* We need the part command */
 #define CONFIG_PARTITION_UUIDS
 #define CONFIG_CMD_PART
-- 
1.9.1

[U-Boot] [PATCH] config_distro_bootcmd.h: add note on error handling

[Tom Rini]

On Tue, Mar 10, 2015 at 03:40:58PM -0600, Stephen Warren wrote:

> From: Stephen Warren <swarren@nvidia.com>
> 
> This should make it more clear why there appear to be C pre-processor
> symbols in the file that contain mixed case. They're really error
> messages.
> 
> Suggested-by: Simon Glass <sjg@chromium.org>
> Signed-off-by: Stephen Warren <swarren@nvidia.com>

Reviewed-by: Tom Rini <trini@konsulko.com>

-- 
Tom
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[U-Boot] [PATCH] config_distro_bootcmd.h: add note on error handling

[Stephen Warren]

On 03/11/2015 09:51 AM, Tom Rini wrote:
> On Tue, Mar 10, 2015 at 03:40:58PM -0600, Stephen Warren wrote:
>
>> From: Stephen Warren <swarren@nvidia.com>
>>
>> This should make it more clear why there appear to be C pre-processor
>> symbols in the file that contain mixed case. They're really error
>> messages.
>>
>> Suggested-by: Simon Glass <sjg@chromium.org>
>> Signed-off-by: Stephen Warren <swarren@nvidia.com>
>
> Reviewed-by: Tom Rini <trini@konsulko.com>

Thanks. It looks like you usually apply the patches to this file rather 
than acking it for someone else to take. Was your reviewed-by just a 
hint you're waiting for e.g. Simon to review it too?

[U-Boot] [PATCH] config_distro_bootcmd.h: add note on error handling

[Tom Rini]

On Wed, Mar 11, 2015 at 10:22:23AM -0600, Stephen Warren wrote:
> On 03/11/2015 09:51 AM, Tom Rini wrote:
> >On Tue, Mar 10, 2015 at 03:40:58PM -0600, Stephen Warren wrote:
> >
> >>From: Stephen Warren <swarren@nvidia.com>
> >>
> >>This should make it more clear why there appear to be C pre-processor
> >>symbols in the file that contain mixed case. They're really error
> >>messages.
> >>
> >>Suggested-by: Simon Glass <sjg@chromium.org>
> >>Signed-off-by: Stephen Warren <swarren@nvidia.com>
> >
> >Reviewed-by: Tom Rini <trini@konsulko.com>
> 
> Thanks. It looks like you usually apply the patches to this file
> rather than acking it for someone else to take. Was your reviewed-by
> just a hint you're waiting for e.g. Simon to review it too?

Yes, thanks :)

-- 
Tom
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[U-Boot] [PATCH] config_distro_bootcmd.h: add note on error handling

[Simon Glass]

On 10 March 2015 at 15:40, Stephen Warren <swarren@wwwdotorg.org> wrote:
> From: Stephen Warren <swarren@nvidia.com>
>
> This should make it more clear why there appear to be C pre-processor
> symbols in the file that contain mixed case. They're really error
> messages.
>
> Suggested-by: Simon Glass <sjg@chromium.org>
> Signed-off-by: Stephen Warren <swarren@nvidia.com>
> ---
>  include/config_distro_bootcmd.h | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/include/config_distro_bootcmd.h b/include/config_distro_bootcmd.h
> index 07a0b3b23472..73f093f9eaf5 100644
> --- a/include/config_distro_bootcmd.h
> +++ b/include/config_distro_bootcmd.h
> @@ -10,6 +10,22 @@
>  #ifndef _CONFIG_CMD_DISTRO_BOOTCMD_H
>  #define _CONFIG_CMD_DISTRO_BOOTCMD_H
>
> +/*
> + * A note on error handling: It is possible for BOOT_TARGET_DEVICES to
> + * reference a device that is not enabled in the U-Boot configuration, e.g.
> + * it may include MMC in the list without CONFIG_CMD_MMC being enabled. Given
> + * that BOOT_TARGET_DEVICES is a macro that's expanded by the C pre-processor
> + * at compile time, it's not  possible to detect and report such problems via
> + * a simple #ifdef/#error combination. Still, the code needs to report errors.
> + * The best way I've found to do this is to make BOOT_TARGET_DEVICES expand to
> + * reference a non-existent symbol, and have the name of that symbol encode
> + * the error message. Consequently, this file contains references to e.g.
> + * BOOT_TARGET_DEVICES_references_MMC_without_CONFIG_CMD_MMC. Given the
> + * prevalence of capitals here, this looks like a pre-processor macro and
> + * hence seems like it should be all capitals, but it's really an error
> + * message that includes some other pre-processor symbols in the text.
> + */
> +
>  /* We need the part command */
>  #define CONFIG_PARTITION_UUIDS
>  #define CONFIG_CMD_PART

Very clear thank you.

Reviewed-by: Simon Glass <sjg@chromium.org>

[U-Boot] config_distro_bootcmd.h: add note on error handling

[Tom Rini]

On Tue, Mar 10, 2015 at 03:40:58PM -0600, Stephen Warren wrote:

> From: Stephen Warren <swarren@nvidia.com>
> 
> This should make it more clear why there appear to be C pre-processor
> symbols in the file that contain mixed case. They're really error
> messages.
> 
> Suggested-by: Simon Glass <sjg@chromium.org>
> Signed-off-by: Stephen Warren <swarren@nvidia.com>
> Reviewed-by: Tom Rini <trini@konsulko.com>
> Reviewed-by: Simon Glass <sjg@chromium.org>

Applied to u-boot/master, thanks!

-- 
Tom
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