linux-riscv.lists.infradead.org archive mirror
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@lst.de>
To: Palmer Dabbelt <palmer@sifive.com>,
	Paul Walmsley <paul.walmsley@sifive.com>
Cc: linux-mm@kvack.org, Damien Le Moal <Damien.LeMoal@wdc.com>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH 10/17] riscv: read the hart ID from mhartid on boot
Date: Mon, 24 Jun 2019 07:43:04 +0200	[thread overview]
Message-ID: <20190624054311.30256-11-hch@lst.de> (raw)
In-Reply-To: <20190624054311.30256-1-hch@lst.de>

From: Damien Le Moal <Damien.LeMoal@wdc.com>

When in M-Mode, we can use the mhartid CSR to get the ID of the running
HART. Doing so, direct M-Mode boot without firmware is possible.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/riscv/kernel/head.S | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index e5fa5481aa99..a4c170e41a34 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -18,6 +18,14 @@ ENTRY(_start)
 	csrw CSR_XIE, zero
 	csrw CSR_XIP, zero
 
+#ifdef CONFIG_M_MODE
+	/*
+	 * The hartid in a0 is expected later on, and we have no firmware
+	 * to hand it to us.
+	 */
+	csrr a0, mhartid
+#endif
+
 	/* Load the global pointer */
 .option push
 .option norelax
-- 
2.20.1


_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

  parent reply	other threads:[~2019-06-24  5:43 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-24  5:42 RISC-V nommu support v2 Christoph Hellwig
2019-06-24  5:42 ` [PATCH 01/17] mm: provide a print_vma_addr stub for !CONFIG_MMU Christoph Hellwig
2019-06-24  5:42 ` [PATCH 02/17] mm: stub out all of swapops.h " Christoph Hellwig
2019-06-24  5:42 ` [PATCH 03/17] mm/nommu: fix the MAP_UNINITIALIZED flag Christoph Hellwig
2019-06-24  5:42 ` [PATCH 04/17] irqchip/sifive-plic: set max threshold for ignored handlers Christoph Hellwig
2019-06-24  5:42 ` [PATCH 05/17] riscv: use CSR_SATP instead of the legacy sptbr name in switch_mm Christoph Hellwig
2019-07-01 18:53   ` Atish Patra
2019-06-24  5:43 ` [PATCH 06/17] riscv: refactor the IPI code Christoph Hellwig
2019-06-24  5:43 ` [PATCH 07/17] riscv: abstract out CSR names for supervisor vs machine mode Christoph Hellwig
2019-07-01 18:37   ` Atish Patra
2019-06-24  5:43 ` [PATCH 08/17] riscv: improve the default power off implementation Christoph Hellwig
2019-07-01 21:07   ` Atish Patra
2019-06-24  5:43 ` [PATCH 09/17] riscv: provide a flat entry loader Christoph Hellwig
2019-06-24  5:43 ` Christoph Hellwig [this message]
2019-07-01 21:15   ` [PATCH 10/17] riscv: read the hart ID from mhartid on boot Atish Patra
2019-06-24  5:43 ` [PATCH 11/17] riscv: provide native clint access for M-mode Christoph Hellwig
2019-06-24  5:43 ` [PATCH 12/17] riscv: implement remote sfence.i natively " Christoph Hellwig
2019-06-24  5:43 ` [PATCH 13/17] riscv: poison SBI calls " Christoph Hellwig
2019-06-24  5:43 ` [PATCH 14/17] riscv: don't allow selecting SBI-based drivers " Christoph Hellwig
2019-06-24  5:43 ` [PATCH 15/17] riscv: use the correct interrupt levels " Christoph Hellwig
2019-06-24  5:43 ` [PATCH 16/17] riscv: clear the instruction cache and all registers when booting Christoph Hellwig
2019-07-01 21:26   ` Atish Patra
2019-07-08  8:26     ` Palmer Dabbelt
2019-08-13 15:40       ` Christoph Hellwig
2019-08-13 15:37     ` hch
2019-06-24  5:43 ` [PATCH 17/17] riscv: add nommu support Christoph Hellwig
2019-07-12 14:52   ` Vladimir Murzin
2019-06-24 11:47 ` RISC-V nommu support v2 Vladimir Murzin
2019-06-24 11:54   ` Christoph Hellwig
2019-06-24 13:08     ` Vladimir Murzin
2019-06-24 13:16       ` Christoph Hellwig
2019-06-25  7:31       ` Palmer Dabbelt
2019-06-25 12:37         ` Vladimir Murzin
2019-07-01  6:56 ` Christoph Hellwig
2019-07-01 16:06   ` Paul Walmsley

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190624054311.30256-11-hch@lst.de \
    --to=hch@lst.de \
    --cc=Damien.LeMoal@wdc.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-riscv@lists.infradead.org \
    --cc=palmer@sifive.com \
    --cc=paul.walmsley@sifive.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).