This adds some documentation on when to use a static volume. After reading the documentation I had decided to make my squashfs root static without knowing about a significant penalty to the boot time. I have made some additions to the documentation to make this a little bit more clear. Best Regards, Mark Deneen
From a8cc7820fc599b9e7f366f89a194c676cc697b47 Mon Sep 17 00:00:00 2001 From: Mark Deneen <mdeneen@xxxxxxxxxxxxxx> Date: Fri, 3 Apr 2020 16:27:07 -0400 Subject: [PATCH] additional notes on choosing between a static and a dynamic volume create mode 100644 0001-Fix-hyperlink-to-UBI-block-device.patch diff --git a/0001-Fix-hyperlink-to-UBI-block-device.patch b/0001-Fix-hyperlink-to-UBI-block-device.patch new file mode 100644 index 0000000..ad94a6c --- /dev/null +++ b/0001-Fix-hyperlink-to-UBI-block-device.patch @@ -0,0 +1,22 @@ +From 4349c7156a7343279c8a1e66b0a651071da4df85 Mon Sep 17 00:00:00 2001 +From: Mark Deneen <mdeneen@xxxxxxxxxxxxxx> +Date: Fri, 3 Apr 2020 15:54:04 -0400 +Subject: [PATCH] Fix hyperlink to UBI block device + + +diff --git a/faq/ubi.xml b/faq/ubi.xml +index f9a76b3..551959d 100644 +--- a/faq/ubi.xml ++++ b/faq/ubi.xml +@@ -168,7 +168,7 @@ mount read-only file systems.</p> + + <p>Yes. UBI allows to create a read-only block device on top of a UBI volume + which is suitable for read-only, block-oriented file systems, such as squashfs. +-See the <a href="..doc/ubi.html#L_block">UBI block device</a> section for more details.</p> ++See the <a href="../doc/ubi.html#L_block">UBI block device</a> section for more details.</p> + + <h2><a name="L_format_mtd"> + Do I have to format my empty flash before running UBI on top of it? +-- +2.20.1 + diff --git a/doc/ubi.xml b/doc/ubi.xml index 568a66e..1290735 100644 --- a/doc/ubi.xml +++ b/doc/ubi.xml @@ -109,6 +109,13 @@ volumes. Static volumes are read-only and their contents are protected by upper layers (e.g., a file-system) are responsible for ensuring data integrity.</p> +<p>Static volumes are typically used for the kernel, initramfs, and dtb. +Larger static volumes may incur a significant penalty when opening, as the +<code>CRC-32</code> needs to be calculated at this time. If you are looking +to use static volumes for anything besides the kernel, initramfs, or dtb you +are likely doing something wrong and would be better off using a dynamic volume +instead.</p> + <p>UBI is aware of bad eraseblocks (i.e. portions of flash which wear out over time) and frees upper-level software from having to handle bad eraseblocks itself. UBI has a pool of reserved physical eraseblocks, and -- 2.20.1
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