关于am3359上emmc的支持问题

有看过TRM手册的26.1.7.5 MMC/SD Cards章节吗？里面的第二小节说的就特别指出的是你现在的这种情况。大于4G的MMC必须接在MMC1才能支持启动。

Each interface has booting restrictions on which type of memory it supports: -
• MMC0 supports booting from the MMC/SD card cage and also supports booting from
eMMC/eSD/managed NAND memory devices with less than 4GB capacity.
• MMC1 supports booting from eMMC/eSD/managed NAND memory device with 4GB capacity or
greater.
The restriction is a result of many eMMC devices not being compliant with the eMMC v4.41 specification.
If you have the need to boot from two different card cages, many MMC/SD cards will boot from MMC1, but
for maximum compatibility only MMC0 should be used to boot from the card cage. Similarly for maximum
compatibility, booting from eMMC/eSD/managed NAND should only be performed on MMC1.
Note that the above restrictions only apply to booting from each port. Drivers can be written for either port
to support any desired interface.

感谢您的回复。您说的这个内容我也看过，基于以下两句:The restriction is a result of many eMMC devices not being compliant with the eMMC v4.41 specification.

Note that the above restrictions only apply to booting from each port. Drivers can be written for either port
to support any desired interface.这两句我的理解是这个限制是对于不支持v4.41规格的emmc，而我们的设备是支持的，并且我也见过有数字板是4GB的emmc接在mmc0上是可以正常工作的。我现在很困惑的是，即使mmc0上不支持从emmc启动，那也不至于连设备都识别不到吧，Linux内核起来之后设备还是可以识别到的呢，所以我想请教下，是不是有什么我们需要注意的配置，或者需要修改uboot中对emmc设备的支持？

请问您现在eMMC是什么型号的，用的是什么协议？

若是4.41以上的协议，bootrom是不会从MMC0上启动eMMC的。

在吗 能否分享下 你在AM335X上用EMM5.0 如下命令的值，我看看 bus用的4bit还是8bit

cat /sys/kernel/debug/mmc*/ios