[coreboot-gerrit] Change in coreboot[master]: Turn CBMEM console into a ring buffer that can persist acros...

[Julius Werner (Code Review)]

Julius Werner has posted comments on this change. ( https://review.coreboot.org/18301 )

Change subject: Turn CBMEM console into a ring buffer that can persist across reboots
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Patch Set 5:

(7 comments)

https://review.coreboot.org/#/c/18301/5/payloads/libpayload/drivers/cbmem_console.c
File payloads/libpayload/drivers/cbmem_console.c:

PS5, Line 67: uint32_t
> size_t
Done


https://review.coreboot.org/#/c/18301/5/src/lib/cbmem_console.c
File src/lib/cbmem_console.c:

PS5, Line 80: cbm_cons_p->size < CURSOR_MASK
> This is kinda odd to me. cursor is an index that can have the value of [0, 
This restriction helps prevent overflows into bit 24 in cbmemc_tx_byte() below. I can rewrite that as you suggested and then allow another byte here. I just assumed no one would ever want anywhere near 16MB anyway.

(Then again, maybe with a lot of debug output... actually, let me throw in 4 more bits just to be sure.)


PS5, Line 84: inline
> Any reason you didn't remove this inline but you did on current_console() a
No, overlooked that one, thanks. I'm assuming that the compiler will do a better job deciding what's worth inlining in all these cases so we shouldn't specify it explicitly unless there's a good reason.


Line 120: 	 * not disturb flags (and we check for overflow right after). */
> I just wrote out the following as an alternative. Your way works, but it as
Okay, fair enough, that looks better.


PS5, Line 162: preram
> fwiw, this object isn't exactly preram in ramstage and postcar situations.
Renamed.


Line 166: 		copy_console_buffer(preram_cons_p);
> Just a thought: make copy_console_buffer() check for NULL src then you can 
Done


https://review.coreboot.org/#/c/18301/5/util/cbmem/cbmem.c
File util/cbmem/cbmem.c:

Line 643: 	if (console_p->cursor & CBMC_OVERFLOW) {
> The cursor value should still be checked in this path because cursor could 
That shouldn't really happen with the new code, but I guess it doesn't hurt to check.


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Gerrit-MessageType: comment
Gerrit-Change-Id: Ifcbf59d58e1ad20995b98d111c4647281fbb45ff
Gerrit-PatchSet: 5
Gerrit-Project: coreboot
Gerrit-Branch: master
Gerrit-Owner: Julius Werner <jwerner at chromium.org>
Gerrit-Reviewer: Aaron Durbin <adurbin at chromium.org>
Gerrit-Reviewer: Alexander Couzens <lynxis at fe80.eu>
Gerrit-Reviewer: Furquan Shaikh <furquan at google.com>
Gerrit-Reviewer: Julius Werner <jwerner at chromium.org>
Gerrit-Reviewer: Kevin O'Connor <kevin at koconnor.net>
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