On 5/29/26 05:36, [email protected] wrote:
On Thu, May 28, 2026 at 11:28:33AM +0200, Neil Armstrong wrote:
Hi,
On 5/28/26 03:20, [email protected] wrote:
From: Denis Mukhin <[email protected]>
Add flush command implementation along with a high-level
disk_blk_flush() API to be called at certain checkpoints
during the boot (e.g. updating custom bootflow flags stored
on NVMe).
First general comment, please split the patch by adding the
flush infrastructure first and then the nvme support.
Will do, thanks.
The for NVMe, can it support write-through like SCSI FUA (Force Unit
Access) which bypasses the cache on writes, with slower writes
but safer and simpler than calling a flush before OS boot.
Yes, I've seen there was FUA patch [1], which was then reverted [2].
For our purposes, flush seems to be enough: the use case is
updating NVMe-backed boot counter from a custom bootflow.
OK the FUA was reverted because Bin's comment was not adressed:
https://lore.kernel.org/u-boot/caeuhbmu02gnqeefuqnrsj8r5xezkmktualp1+bmbyqndztu...@mail.gmail.com/
I would prefer having FUA added so all board could have this enabled
and not have to update their boot flow to call flush, this was basically
why the SCSI FUA was enabled.
As Bin's comment, perhaps a way would be to disable the Write Cache if
the cache is present as init time (WCE), and it's even simpler, or
get the enable state of the WC and use FUA if enabled.
Because the same question remains with the flush command, it's
only valid if the WC is present and is enabled.
Thanks,
Neil
[1]
https://lore.kernel.org/u-boot/20211019104049.v3.1.Ic581ec99f46b6dfa2e0b1922e670a333ac859e82@changeid/
[2]
https://lore.kernel.org/u-boot/cagi-rul96gk5nfhx73uqqd_4sfbyt3gnwqhfphps+h58s20...@mail.gmail.com/
[..]
/**
* blk_find_device() - Find a block device
*
@@ -559,6 +577,16 @@ static inline ulong blk_derase(struct blk_desc *block_dev,
lbaint_t start,
return block_dev->block_erase(block_dev, start, blkcnt);
}
+static inline ulong blk_dflush(struct blk_desc *block_dev)
+{
+ blkcache_invalidate(block_dev->uclass_id, block_dev->devnum);
Call blkcache_invalidate only if flush cmd is supported
Ack.
+
+ if (block_dev->block_flush)
+ return block_dev->block_flush(block_dev);
+
+ return 0;
Why do you return success here and not from blk_flush() when flush is not
supported?
Will update.
Thanks,
Denis
