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Firmware 8 byte alignment

This problem I have I really don't understand. I've got some code which runs fine. Is encorperates an SD-card interface (NXP/Martin Thomas/CHaN). At some point I found out that a certain SD-card was recognized poorly: it took my app 10 extra seconds to initialize the SD-card subsystem. Adding debug info I tried to figure out the cause. It's the MCI_Send_Status() from mci.c which takes so long.

What amazes me is that by just adding 8 bytes of arbitrary code (e.g. by extending a const string with 8 characters), in a seemingly arbitrary module (.o file), makes my app boot quickly again. Add by adding 8 more bytes slow, etc.

So it seems to be some delicate alignment issue in ROM. But what exactly is going on? Has anyone encountered similar issues?

LPC 2386

Thanks, Mark

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