Whether Armv7-A has a Write Buffer

Thank you.

I think this is about store buffer not write buffer. Store buffer is mainly used to hold store operation to Cache after committed by Load Store Unit. Write buffer is used to hold store operation to main memory. I think the two are different.

Thank you.

I think this is about store buffer not write buffer. Store buffer is mainly used to hold store operation to Cache after committed by Load Store Unit. Write buffer is used to hold store operation to main memory. I think the two are different.

The TRM mentions three types of buffers:

• linefill buffers
• eviction buffer
• store buffer

The last one is your write buffer.

It will merge writes from L/S unit to nearby memory locations.

It can be drained with a DSB.

See https://community.arm.com/tools/f/discussions/1031/armv7-34-write-buffer-34-issue

OK.

Thank you very much.

I have another question. DMB is enough to drain store buffer, am I right?

DMB ensures ordering only.

It will not "wait" for the write buffer.

See https://community.arm.com/processors/f/discussions/3287/questions-regarding-dmb-dsb-and-isb

Thank you!