On 22/06/2023 10:22, Julien Grall wrote:
Hi Ayan,
Hi Julien,
On 22/06/2023 09:59, Ayan Kumar Halder wrote:
On 20/06/2023 21:43, Julien Grall wrote:
Hi Ayan,
Hi Julien,
On 20/06/2023 19:28, Ayan Kumar Halder wrote:
On 20/06/2023 17:41, Julien Grall wrote:
Hi,
Hi Julien,
On 20/06/2023 16:17, Ayan Kumar Halder wrote:
Add a special configuration (CONFIG_AARCH32_V8R) to setup the
Cortex-R52
specifics.
Cortex-R52 is an Arm-V8R AArch32 processor.
Refer ARM DDI 0487I.a ID081822, G8-9647, G8.2.112 MIDR,
bits[31:24] = 0x41 , Arm Ltd
bits[23:20] = Implementation defined
bits[19:16] = 0xf , Arch features are individually identified
bits[15:4] = Implementation defined
bits[3:0] = Implementation defined
Thus, the processor id is 0x410f0000 and the processor id mask is
0xff0f0000
Also, there is no special initialization required for R52.
Are you saying that Xen upstream + this patch will boot on
Cortex-R52?
This patch will help for earlyboot of Xen. With this patch,
cpu_init() will work on Cortex-R52.
There will be changes required for the MPU configuration, but that
will be sent after Penny's patch serie "[PATCH v2 00/41] xen/arm:
Add Armv8-R64 MPU support to Xen - Part#1" is upstreamed.
My aim is to extract the non-dependent changes and send them for
review.
I can review the patch. But I am not willing to merge it as it gives
the false impression that Xen would boot on Cortex-R52.
In fact, I think this patch should only be merged once we have all
the MPU merged.
IMHO, patches are independent are rework (e.g. code split...) that
would help the MPU.
Yes, that's exactly what I intend to do. I will send out the patches
(similar to this) which will not be impacted by the MPU changes.
So, that both as an author/reviewer, it helps to restrict MPU serie
to only MPU specific changes. >
Can you suggest some change to the commit message, so that we can
commit it (without giving any false impression that Xen boots on
Cortex-R52) >
May be adding this line to the commit message helps ? >
"However, Xen does not fully boot on Cortex-R52 as it requires MPU
support which is under review. >
Once Xen is supported on Cortex-R52, SUPPORT.md will be amended to
reflect it."
While writing an answer for this patch, I was actually wondering
whether the CPU allowlist still make sense for the 32-bit ARMv8-R?
From Armv7-A, we needed it because some CPUs need specific quirk when
booting. But it would be best if we can get rid of it for 32-bit ARMv8-R.
Looking at your patch, your merely providing stubs. Do you have any
plan to fill them up?
Actually, I would use cr52_init in a later patch to write to CNTFRQ. See
below :-
+#define XPAR_CPU_CORTEXR52_0_TIMESTAMP_CLK_FREQ 800000U
+
cr52_init:
+ /*
+ * Set counter frequency 800 KHZ
+ *
+ * Set counter frequency, CNTFRQ
+ */
+ ldr r0,=XPAR_CPU_CORTEXR52_0_TIMESTAMP_CLK_FREQ
+ mrc 15,0,r1,c14,c0,0 /* Read CNTFRQ */
+ cmp r1,#0
+ /* Set only if the frequency read is 0 */
+ mcreq 15,0,r0,c14,c0,0 /* Write CNTFRQ */
+
mov pc, lr
- Ayan
Cheers,
